diff --git a/README.md b/README.md
index 4022e362cd..12ddad6e45 100644
--- a/README.md
+++ b/README.md
@@ -169,6 +169,14 @@ flank:
   ## Default: false
   # smart-flank-disable-upload: false
 
+  ## Enable using average time from previous tests duration when using SmartShard and tests did not run before.
+  ## Default: false
+  # use-average-test-time-for-new-tests: true
+
+  ## Set default test time used for calculating shards.
+  ## Default: 120.0
+  # default-test-time: 15
+
   ## Disables sharding. Useful for parameterized tests.
   # disable-sharding: false
 
@@ -385,6 +393,14 @@ flank:
   ## Default: false
   # smart-flank-disable-upload: false
 
+  ## Enable using average time from previous tests duration when using SmartShard and tests did not run before.
+  ## Default: false
+  # use-average-test-time-for-new-tests: true
+
+  ## Set default test time used for calculating shards.
+  ## Default: 120.0
+  # default-test-time: 15
+
   ## Disables sharding. Useful for parameterized tests.
   # disable-sharding: false
 
diff --git a/test_runner/flank.ios.yml b/test_runner/flank.ios.yml
index f0e7f5db55..0993182c70 100644
--- a/test_runner/flank.ios.yml
+++ b/test_runner/flank.ios.yml
@@ -101,6 +101,14 @@ flank:
   ## Default: false
   # smart-flank-disable-upload: false
 
+  ## Enable using average time from previous tests duration when using SmartShard and tests did not run before.
+  ## Default: false
+  # use-average-test-time-for-new-tests: true
+
+  ## Set default test time used for calculating shards.
+  ## Default: 120.0
+  # default-test-time: 15
+
   ## Disables sharding. Useful for parameterized tests.
   # disable-sharding: false
 
diff --git a/test_runner/flank.yml b/test_runner/flank.yml
index 9dca0ee356..436d9cf966 100644
--- a/test_runner/flank.yml
+++ b/test_runner/flank.yml
@@ -161,6 +161,14 @@ flank:
   ## Default: false
   # smart-flank-disable-upload: false
 
+  ## Enable using average time from previous tests duration when using SmartShard and tests did not run before.
+  ## Default: false
+  # use-average-test-time-for-new-tests: true
+
+  ## Set default test time used for calculating shards.
+  ## Default: 120.0
+  # default-test-time: 15
+
   ## Disables sharding. Useful for parameterized tests.
   # disable-sharding: false
 
diff --git a/test_runner/src/main/kotlin/ftl/args/AndroidArgs.kt b/test_runner/src/main/kotlin/ftl/args/AndroidArgs.kt
index faa66e1362..03133a3a43 100644
--- a/test_runner/src/main/kotlin/ftl/args/AndroidArgs.kt
+++ b/test_runner/src/main/kotlin/ftl/args/AndroidArgs.kt
@@ -58,6 +58,8 @@ AndroidArgs
       num-test-runs: $repeatTests
       smart-flank-gcs-path: $smartFlankGcsPath
       smart-flank-disable-upload: $smartFlankDisableUpload
+      default-test-time: $defaultTestTime
+      use-average-test-time-for-new-tests: $useAverageTestTimeForNewTests
       files-to-download:${ArgsToString.listToString(filesToDownload)}
       test-targets-always-run:${ArgsToString.listToString(testTargetsAlwaysRun)}
       disable-sharding: $disableSharding
diff --git a/test_runner/src/main/kotlin/ftl/args/CommonArgs.kt b/test_runner/src/main/kotlin/ftl/args/CommonArgs.kt
index 7112851a31..dff7e91f5e 100644
--- a/test_runner/src/main/kotlin/ftl/args/CommonArgs.kt
+++ b/test_runner/src/main/kotlin/ftl/args/CommonArgs.kt
@@ -34,5 +34,7 @@ data class CommonArgs(
     override val ignoreFailedTests: Boolean,
     override val keepFilePath: Boolean,
     override val outputStyle: OutputStyle,
-    override val disableResultsUpload: Boolean
+    override val disableResultsUpload: Boolean,
+    override val defaultTestTime: Double,
+    override val useAverageTestTimeForNewTests: Boolean,
 ) : IArgs
diff --git a/test_runner/src/main/kotlin/ftl/args/CreateCommonArgs.kt b/test_runner/src/main/kotlin/ftl/args/CreateCommonArgs.kt
index 82180b6a27..0838411662 100644
--- a/test_runner/src/main/kotlin/ftl/args/CreateCommonArgs.kt
+++ b/test_runner/src/main/kotlin/ftl/args/CreateCommonArgs.kt
@@ -41,7 +41,9 @@ fun CommonConfig.createCommonArgs(
     filesToDownload = flank.filesToDownload!!,
     disableSharding = flank.disableSharding!!,
     localResultDir = flank.localResultsDir!!,
-    disableResultsUpload = flank.disableResultsUpload!!
+    disableResultsUpload = flank.disableResultsUpload!!,
+    defaultTestTime = flank.defaultTestTime!!,
+    useAverageTestTimeForNewTests = flank.useAverageTestTimeForNewTests!!
 ).apply {
     ArgsHelper.createJunitBucket(project, smartFlankGcsPath)
 }
diff --git a/test_runner/src/main/kotlin/ftl/args/IArgs.kt b/test_runner/src/main/kotlin/ftl/args/IArgs.kt
index 1e2cc949d4..d7aa8f2725 100644
--- a/test_runner/src/main/kotlin/ftl/args/IArgs.kt
+++ b/test_runner/src/main/kotlin/ftl/args/IArgs.kt
@@ -59,6 +59,9 @@ interface IArgs {
     val inVirtualRange: Boolean
         get() = maxTestShards in AVAILABLE_VIRTUAL_SHARD_COUNT_RANGE
 
+    val defaultTestTime: Double
+    val useAverageTestTimeForNewTests: Boolean
+
     fun useLocalResultDir() = localResultDir != defaultLocalResultsDir
 
     companion object {
diff --git a/test_runner/src/main/kotlin/ftl/args/IosArgs.kt b/test_runner/src/main/kotlin/ftl/args/IosArgs.kt
index fdf625b3db..98449288b3 100644
--- a/test_runner/src/main/kotlin/ftl/args/IosArgs.kt
+++ b/test_runner/src/main/kotlin/ftl/args/IosArgs.kt
@@ -43,6 +43,8 @@ IosArgs
       num-test-runs: $repeatTests
       smart-flank-gcs-path: $smartFlankGcsPath
       smart-flank-disable-upload: $smartFlankDisableUpload
+      default-test-time: $defaultTestTime
+      use-average-test-time-for-new-tests: $useAverageTestTimeForNewTests
       test-targets-always-run:${ArgsToString.listToString(testTargetsAlwaysRun)}
       files-to-download:${ArgsToString.listToString(filesToDownload)}
       keep-file-path: $keepFilePath
diff --git a/test_runner/src/main/kotlin/ftl/config/common/CommonFlankConfig.kt b/test_runner/src/main/kotlin/ftl/config/common/CommonFlankConfig.kt
index fbbf20384c..824006927c 100644
--- a/test_runner/src/main/kotlin/ftl/config/common/CommonFlankConfig.kt
+++ b/test_runner/src/main/kotlin/ftl/config/common/CommonFlankConfig.kt
@@ -7,6 +7,7 @@ import ftl.args.ArgsHelper
 import ftl.args.yml.IYmlKeys
 import ftl.config.Config
 import ftl.config.FtlConstants
+import ftl.shard.DEFAULT_TEST_TIME_SEC
 import picocli.CommandLine
 
 /** Flank specific parameters for both iOS and Android */
@@ -140,6 +141,20 @@ data class CommonFlankConfig @JsonIgnore constructor(
     @set:JsonProperty("disable-results-upload")
     var disableResultsUpload: Boolean? by data
 
+    @set:CommandLine.Option(
+        names = ["--default-test-time"],
+        description = ["Set default test time used for calculating shards."]
+    )
+    @set:JsonProperty("default-test-time")
+    var defaultTestTime: Double? by data
+
+    @set:CommandLine.Option(
+        names = ["--use-average-test-time-for-new-tests"],
+        description = ["Enable using average time from previous tests duration when using SmartShard and tests did not run before."]
+    )
+    @set:JsonProperty("use-average-test-time-for-new-tests")
+    var useAverageTestTimeForNewTests: Boolean? by data
+
     constructor() : this(mutableMapOf<String, Any?>().withDefault { null })
 
     companion object : IYmlKeys {
@@ -184,6 +199,8 @@ data class CommonFlankConfig @JsonIgnore constructor(
             keepFilePath = false
             outputStyle = null
             disableResultsUpload = false
+            defaultTestTime = DEFAULT_TEST_TIME_SEC
+            useAverageTestTimeForNewTests = false
         }
     }
 }
diff --git a/test_runner/src/main/kotlin/ftl/shard/Shard.kt b/test_runner/src/main/kotlin/ftl/shard/Shard.kt
index 19350fe858..76b1a77433 100644
--- a/test_runner/src/main/kotlin/ftl/shard/Shard.kt
+++ b/test_runner/src/main/kotlin/ftl/shard/Shard.kt
@@ -45,7 +45,7 @@ fun createShardsByShardCount(
     val maxShards = maxShards(args.maxTestShards, forcedShardCount)
 
     val previousMethodDurations = createTestMethodDurationMap(oldTestResult, args)
-    val testCases = createTestCases(testsToRun, previousMethodDurations)
+    val testCases = createTestCases(testsToRun, previousMethodDurations, args)
         .sortedByDescending(TestMethod::time) // We want to iterate over testcase going from slowest to fastest
 
     val testCount = getNumberOfNotIgnoredTestCases(testCases)
diff --git a/test_runner/src/main/kotlin/ftl/shard/ShardCount.kt b/test_runner/src/main/kotlin/ftl/shard/ShardCount.kt
index a6b6eeb10e..914ec5dd8a 100644
--- a/test_runner/src/main/kotlin/ftl/shard/ShardCount.kt
+++ b/test_runner/src/main/kotlin/ftl/shard/ShardCount.kt
@@ -26,14 +26,26 @@ private fun calculateShardCount(
     testsToRun: List<FlankTestMethod>,
     oldTestResult: JUnitTestResult,
     args: IArgs
-): Int = calculateShardCount(
-    args = args,
-    testsTotalTime = testTotalTime(testsToRun, createTestMethodDurationMap(oldTestResult, args)),
-    testsToRunCount = testsToRun.size
-)
-
-private fun testTotalTime(testsToRun: List<FlankTestMethod>, previousMethodDurations: Map<String, Double>): Double =
-    testsToRun.sumByDouble { flankTestMethod -> getTestMethodTime(flankTestMethod, previousMethodDurations) }
+): Int {
+    val previousMethodDurations = createTestMethodDurationMap(oldTestResult, args)
+    return calculateShardCount(
+        args = args,
+        testsTotalTime = testTotalTime(testsToRun, previousMethodDurations, args.fallbackTestTime(previousMethodDurations)),
+        testsToRunCount = testsToRun.size
+    )
+}
+
+private fun testTotalTime(
+    testsToRun: List<FlankTestMethod>,
+    previousMethodDurations: Map<String, Double>,
+    defaultTestTime: Double
+) = testsToRun.sumByDouble { flankTestMethod ->
+    getTestMethodTime(
+        flankTestMethod,
+        previousMethodDurations,
+        defaultTestTime
+    )
+}
 
 private fun calculateShardCount(
     args: IArgs,
diff --git a/test_runner/src/main/kotlin/ftl/shard/TestCasesCreator.kt b/test_runner/src/main/kotlin/ftl/shard/TestCasesCreator.kt
index 4a4995a59a..6e930829b8 100644
--- a/test_runner/src/main/kotlin/ftl/shard/TestCasesCreator.kt
+++ b/test_runner/src/main/kotlin/ftl/shard/TestCasesCreator.kt
@@ -1,5 +1,6 @@
 package ftl.shard
 
+import ftl.args.IArgs
 import ftl.util.FlankTestMethod
 
 data class TestMethod(
@@ -7,6 +8,21 @@ data class TestMethod(
     val time: Double
 )
 
-fun createTestCases(testsToRun: List<FlankTestMethod>, previousMethodDurations: Map<String, Double>): List<TestMethod> {
-    return testsToRun.map { TestMethod(it.testName, getTestMethodTime(it, previousMethodDurations)) }
+fun createTestCases(
+    testsToRun: List<FlankTestMethod>,
+    previousMethodDurations: Map<String, Double>,
+    args: IArgs,
+): List<TestMethod> {
+    val defaultTestTime = args.fallbackTestTime(previousMethodDurations)
+    return testsToRun
+        .map {
+        TestMethod(
+            name = it.testName,
+            time = getTestMethodTime(
+                flankTestMethod = it,
+                previousMethodDurations = previousMethodDurations,
+                defaultTestTime = defaultTestTime
+            )
+        )
+    }
 }
diff --git a/test_runner/src/main/kotlin/ftl/shard/TestMethodTime.kt b/test_runner/src/main/kotlin/ftl/shard/TestMethodTime.kt
index a1f4cc7779..c70c1f55f6 100644
--- a/test_runner/src/main/kotlin/ftl/shard/TestMethodTime.kt
+++ b/test_runner/src/main/kotlin/ftl/shard/TestMethodTime.kt
@@ -1,18 +1,26 @@
 package ftl.shard
 
-import com.google.common.annotations.VisibleForTesting
+import ftl.args.IArgs
 import ftl.util.FlankTestMethod
 
-// When a test does not have previous results to reference, fall back to this run time.
-@VisibleForTesting
-const val DEFAULT_TEST_TIME_SEC = 120.0
+fun getTestMethodTime(
+    flankTestMethod: FlankTestMethod,
+    previousMethodDurations: Map<String, Double>,
+    defaultTestTime: Double
+) = if (flankTestMethod.ignored) IGNORE_TEST_TIME else previousMethodDurations.getOrElse(flankTestMethod.testName) {
+    defaultTestTime
+}
+
+fun IArgs.fallbackTestTime(
+    previousMethodDurations: Map<String, Double>
+) = if (useAverageTestTimeForNewTests) previousMethodDurations.averageTestTime(defaultTestTime) else defaultTestTime
+
+private fun Map<String, Double>.averageTestTime(defaultTestTime: Double) = values
+    .filter { it > IGNORE_TEST_TIME }
+    .average()
+    .takeIf { !it.isNaN() }
+    ?: defaultTestTime
 
-@VisibleForTesting
 const val IGNORE_TEST_TIME = 0.0
 
-fun getTestMethodTime(flankTestMethod: FlankTestMethod, previousMethodDurations: Map<String, Double>): Double {
-    return if (flankTestMethod.ignored) IGNORE_TEST_TIME else previousMethodDurations.getOrDefault(
-        flankTestMethod.testName,
-        DEFAULT_TEST_TIME_SEC
-    )
-}
+const val DEFAULT_TEST_TIME_SEC = 120.0
diff --git a/test_runner/src/test/kotlin/ftl/args/AndroidArgsTest.kt b/test_runner/src/test/kotlin/ftl/args/AndroidArgsTest.kt
index 08a8b665a0..7a1f601bd1 100644
--- a/test_runner/src/test/kotlin/ftl/args/AndroidArgsTest.kt
+++ b/test_runner/src/test/kotlin/ftl/args/AndroidArgsTest.kt
@@ -108,6 +108,8 @@ class AndroidArgsTest {
           max-test-shards: 7
           shard-time: 60
           num-test-runs: 8
+          default-test-time: 15.0
+          use-average-test-time-for-new-tests: true
           files-to-download:
             - /sdcard/screenshots
             - /sdcard/screenshots2
@@ -317,6 +319,8 @@ AndroidArgs
       num-test-runs: 8
       smart-flank-gcs-path:${' '}
       smart-flank-disable-upload: false
+      default-test-time: 15.0
+      use-average-test-time-for-new-tests: true
       files-to-download:
         - /sdcard/screenshots
         - /sdcard/screenshots2
@@ -382,6 +386,8 @@ AndroidArgs
       num-test-runs: 1
       smart-flank-gcs-path: 
       smart-flank-disable-upload: false
+      default-test-time: 120.0
+      use-average-test-time-for-new-tests: false
       files-to-download:
       test-targets-always-run:
       disable-sharding: false
@@ -1676,6 +1682,61 @@ AndroidArgs
         """.trimIndent()
         AndroidArgs.load(yaml)
     }
+
+    @Test
+    fun `should set defaultTestTime`() {
+        val yaml = """
+        gcloud:
+          app: $appApk
+          test: $testApk
+        flank:
+          max-test-shards: -1
+          default-test-time: 15
+        """.trimIndent()
+        val args = AndroidArgs.load(yaml)
+        assertEquals(args.defaultTestTime, 15.0, 0.01)
+    }
+
+    @Test
+    fun `should set defaultTestTime to default value if not specified`() {
+        val yaml = """
+        gcloud:
+          app: $appApk
+          test: $testApk
+        flank:
+          max-test-shards: -1
+          use-average-test-time-for-new-tests: true
+        """.trimIndent()
+        val args = AndroidArgs.load(yaml)
+        assertEquals(args.defaultTestTime, 120.0, 0.01)
+    }
+
+    @Test
+    fun `should useAverageTestTimeForNewTests set to true`() {
+        val yaml = """
+        gcloud:
+          app: $appApk
+          test: $testApk
+        flank:
+          max-test-shards: -1
+          use-average-test-time-for-new-tests: true
+        """.trimIndent()
+        val args = AndroidArgs.load(yaml)
+        assertTrue(args.useAverageTestTimeForNewTests)
+    }
+
+    @Test
+    fun `should useAverageTestTimeForNewTests set to false by defaul`() {
+        val yaml = """
+        gcloud:
+          app: $appApk
+          test: $testApk
+        flank:
+          max-test-shards: -1
+        """.trimIndent()
+        val args = AndroidArgs.load(yaml)
+        assertFalse(args.useAverageTestTimeForNewTests)
+    }
 }
 
 private fun AndroidArgs.Companion.load(yamlData: String, cli: AndroidRunCommand? = null): AndroidArgs =
diff --git a/test_runner/src/test/kotlin/ftl/args/IosArgsTest.kt b/test_runner/src/test/kotlin/ftl/args/IosArgsTest.kt
index b29ae89aae..0dab070d92 100644
--- a/test_runner/src/test/kotlin/ftl/args/IosArgsTest.kt
+++ b/test_runner/src/test/kotlin/ftl/args/IosArgsTest.kt
@@ -14,6 +14,7 @@ import ftl.test.util.TestHelper.assert
 import ftl.test.util.TestHelper.getPath
 import ftl.test.util.assertThrowsWithMessage
 import ftl.util.FlankConfigurationError
+import org.junit.Assert
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertFalse
 import org.junit.Assume
@@ -68,6 +69,8 @@ class IosArgsTest {
           max-test-shards: 7
           shard-time: 60
           num-test-runs: 8
+          default-test-time: 15.0
+          use-average-test-time-for-new-tests: true
           files-to-download:
             - /sdcard/screenshots
           test-targets-always-run:
@@ -219,6 +222,8 @@ IosArgs
       num-test-runs: 8
       smart-flank-gcs-path:${' '}
       smart-flank-disable-upload: false
+      default-test-time: 15.0
+      use-average-test-time-for-new-tests: true
       test-targets-always-run:
         - a/testGrantPermissions
         - a/testGrantPermissions2
@@ -272,6 +277,8 @@ IosArgs
       num-test-runs: 1
       smart-flank-gcs-path: 
       smart-flank-disable-upload: false
+      default-test-time: 120.0
+      use-average-test-time-for-new-tests: false
       test-targets-always-run:
       files-to-download:
       keep-file-path: false
@@ -960,6 +967,61 @@ IosArgs
         """.trimIndent()
         IosArgs.load(yaml)
     }
+
+    @Test
+    fun `should set defaultTestTime`() {
+        val yaml = """
+        gcloud:
+          test: $testPath
+          xctestrun-file: $testPath
+        flank:
+          max-test-shards: -1
+          default-test-time: 15
+        """.trimIndent()
+        val args = IosArgs.load(yaml)
+        assertEquals(args.defaultTestTime, 15.0, 0.01)
+    }
+
+    @Test
+    fun `should set defaultTestTime to default value if not specified`() {
+        val yaml = """
+        gcloud:
+          test: $testPath
+          xctestrun-file: $testPath
+        flank:
+          max-test-shards: -1
+          use-average-test-time-for-new-tests: true
+        """.trimIndent()
+        val args = IosArgs.load(yaml)
+        assertEquals(args.defaultTestTime, 120.0, 0.01)
+    }
+
+    @Test
+    fun `should useAverageTestTimeForNewTests set to true`() {
+        val yaml = """
+        gcloud:
+          test: $testPath
+          xctestrun-file: $testPath
+        flank:
+          max-test-shards: -1
+          use-average-test-time-for-new-tests: true
+        """.trimIndent()
+        val args = IosArgs.load(yaml)
+        Assert.assertTrue(args.useAverageTestTimeForNewTests)
+    }
+
+    @Test
+    fun `should useAverageTestTimeForNewTests set to false by defaul`() {
+        val yaml = """
+        gcloud:
+          test: $testPath
+          xctestrun-file: $testPath
+        flank:
+          max-test-shards: -1
+        """.trimIndent()
+        val args = IosArgs.load(yaml)
+        assertFalse(args.useAverageTestTimeForNewTests)
+    }
 }
 
 private fun IosArgs.Companion.load(yamlData: String, cli: IosRunCommand? = null): IosArgs =
diff --git a/test_runner/src/test/kotlin/ftl/cli/firebase/test/android/AndroidRunCommandTest.kt b/test_runner/src/test/kotlin/ftl/cli/firebase/test/android/AndroidRunCommandTest.kt
index 0cd8459736..ae3e4d59c7 100644
--- a/test_runner/src/test/kotlin/ftl/cli/firebase/test/android/AndroidRunCommandTest.kt
+++ b/test_runner/src/test/kotlin/ftl/cli/firebase/test/android/AndroidRunCommandTest.kt
@@ -467,4 +467,20 @@ class AndroidRunCommandTest {
 
         assertThat(cmd.obfuscate).isTrue()
     }
+
+    @Test
+    fun `default-test-time parse`() {
+        val cmd = AndroidRunCommand()
+        CommandLine(cmd).parseArgs("--default-test-time=15")
+
+        assertThat(cmd.config.common.flank.defaultTestTime).isEqualTo(15.0)
+    }
+
+    @Test
+    fun `use-average-test-time-for-new-tests parse`() {
+        val cmd = AndroidRunCommand()
+        CommandLine(cmd).parseArgs("--use-average-test-time-for-new-tests")
+
+        assertThat(cmd.config.common.flank.useAverageTestTimeForNewTests).isTrue()
+    }
 }
diff --git a/test_runner/src/test/kotlin/ftl/cli/firebase/test/ios/IosRunCommandTest.kt b/test_runner/src/test/kotlin/ftl/cli/firebase/test/ios/IosRunCommandTest.kt
index 87c47744e3..d71ababfca 100644
--- a/test_runner/src/test/kotlin/ftl/cli/firebase/test/ios/IosRunCommandTest.kt
+++ b/test_runner/src/test/kotlin/ftl/cli/firebase/test/ios/IosRunCommandTest.kt
@@ -321,4 +321,20 @@ class IosRunCommandTest {
 
         assertThat(cmd.obfuscate).isTrue()
     }
+
+    @Test
+    fun `default-test-time parse`() {
+        val cmd = IosRunCommand()
+        CommandLine(cmd).parseArgs("--default-test-time=15")
+
+        assertThat(cmd.config.common.flank.defaultTestTime).isEqualTo(15.0)
+    }
+
+    @Test
+    fun `use-average-test-time-for-new-tests parse`() {
+        val cmd = IosRunCommand()
+        CommandLine(cmd).parseArgs("--use-average-test-time-for-new-tests")
+
+        assertThat(cmd.config.common.flank.useAverageTestTimeForNewTests).isTrue()
+    }
 }
diff --git a/test_runner/src/test/kotlin/ftl/shard/ShardTest.kt b/test_runner/src/test/kotlin/ftl/shard/ShardTest.kt
index 674f655dbe..1db0f0f58a 100644
--- a/test_runner/src/test/kotlin/ftl/shard/ShardTest.kt
+++ b/test_runner/src/test/kotlin/ftl/shard/ShardTest.kt
@@ -178,7 +178,7 @@ class ShardTest {
 
     @Test
     fun `tests annotated with @Ignore should have time 0 and do not hav impact on sharding`() {
-        val androidMockedArgs = mockk<IosArgs>()
+        val androidMockedArgs = mockk<IosArgs>(relaxed = true)
         every { androidMockedArgs.maxTestShards } returns 2
         every { androidMockedArgs.shardTime } returns 10
 
@@ -205,7 +205,7 @@ class ShardTest {
 
     @Test
     fun `tests annotated with @Ignore should not produce additional shards`() {
-        val androidMockedArgs = mockk<IosArgs>()
+        val androidMockedArgs = mockk<IosArgs>(relaxed = true)
         every { androidMockedArgs.maxTestShards } returns IArgs.AVAILABLE_PHYSICAL_SHARD_COUNT_RANGE.last
         every { androidMockedArgs.shardTime } returns -1
 
diff --git a/test_runner/src/test/kotlin/ftl/shard/ShardTestCommon.kt b/test_runner/src/test/kotlin/ftl/shard/ShardTestCommon.kt
index 53674f9c73..6538d918a7 100644
--- a/test_runner/src/test/kotlin/ftl/shard/ShardTestCommon.kt
+++ b/test_runner/src/test/kotlin/ftl/shard/ShardTestCommon.kt
@@ -33,5 +33,7 @@ internal fun mockArgs(maxTestShards: Int, shardTime: Int = 0): IArgs {
     val mockArgs = mockk<IosArgs>()
     every { mockArgs.maxTestShards } returns maxTestShards
     every { mockArgs.shardTime } returns shardTime
+    every { mockArgs.defaultTestTime } returns 120.0
+    every { mockArgs.useAverageTestTimeForNewTests } returns false
     return mockArgs
 }
diff --git a/test_runner/src/test/kotlin/ftl/shard/TestCasesCreatorTest.kt b/test_runner/src/test/kotlin/ftl/shard/TestCasesCreatorTest.kt
index db4d4d9e54..d59a281c92 100644
--- a/test_runner/src/test/kotlin/ftl/shard/TestCasesCreatorTest.kt
+++ b/test_runner/src/test/kotlin/ftl/shard/TestCasesCreatorTest.kt
@@ -1,8 +1,11 @@
 package ftl.shard
 
 import com.google.common.truth.Truth.assertThat
+import ftl.args.IArgs
 import ftl.test.util.FlankTestRunner
 import ftl.util.FlankTestMethod
+import io.mockk.every
+import io.mockk.mockk
 import org.junit.Test
 import org.junit.runner.RunWith
 
@@ -21,9 +24,13 @@ internal class TestCasesCreatorTest {
         // given
         val ignoredTestMethods = testMethods.map { it.copy(ignored = true) }
         val expectedTestTime = IGNORE_TEST_TIME
+        val args = mockk<IArgs> {
+            every { useAverageTestTimeForNewTests } returns true
+            every { defaultTestTime } returns 10.0
+        }
 
         // when
-        val createdTestCases = createTestCases(ignoredTestMethods, mapOf())
+        val createdTestCases = createTestCases(ignoredTestMethods, mapOf(), args)
 
         // then
         createdTestCases.forEach {
@@ -32,12 +39,40 @@ internal class TestCasesCreatorTest {
     }
 
     @Test
-    fun `should create test cases with default time for test methods not found in map`() {
+    fun `should create test cases with provided default time for test methods not found in map`() {
         // given
-        val expectedTestTime = DEFAULT_TEST_TIME_SEC
+        val expectedTestTime = 10.0
+        val args = mockk<IArgs> {
+            every { useAverageTestTimeForNewTests } returns false
+            every { defaultTestTime } returns 10.0
+        }
 
         // when
-        val createdTestCases = createTestCases(testMethods, mapOf())
+        val createdTestCases = createTestCases(testMethods, mapOf(), args)
+
+        // then
+        createdTestCases.forEach {
+            assertThat(it.time).isEqualTo(expectedTestTime)
+        }
+    }
+
+    @Test
+    fun `should create test cases with average time of previous methods for test methods not found in map`() {
+        // given
+        val previousTestMethods = mapOf(
+            "oldA" to 12.0,
+            "oldB" to 6.0,
+            "oldC" to 18.0,
+            "oldD" to 12.0,
+        )
+        val expectedTestTime = previousTestMethods.values.average()
+        val args = mockk<IArgs> {
+            every { useAverageTestTimeForNewTests } returns true
+            every { defaultTestTime } returns 10.0
+        }
+
+        // when
+        val createdTestCases = createTestCases(testMethods, previousTestMethods, args)
 
         // then
         createdTestCases.forEach {
@@ -50,9 +85,13 @@ internal class TestCasesCreatorTest {
         // given
         val previousTestTimeSeconds = 12.0
         val previousMapDuration = testMethods.associate { it.testName to previousTestTimeSeconds }
+        val args = mockk<IArgs> {
+            every { useAverageTestTimeForNewTests } returns true
+            every { defaultTestTime } returns 10.0
+        }
 
         // when
-        val createdTestCases = createTestCases(testMethods, previousMapDuration)
+        val createdTestCases = createTestCases(testMethods, previousMapDuration, args)
 
         // then
         createdTestCases.forEach {