diff --git a/test_runner/regress/test_sharding.py b/test_runner/regress/test_sharding.py
index bc43bc77fa..f8770e70fe 100644
--- a/test_runner/regress/test_sharding.py
+++ b/test_runner/regress/test_sharding.py
@@ -198,8 +198,8 @@ def test_sharding_split_compaction(neon_env_builder: NeonEnvBuilder, failpoint:
         # disable background compaction and GC. We invoke it manually when we want it to happen.
         "gc_period": "0s",
         "compaction_period": "0s",
-        # create image layers eagerly, so that GC can remove some layers
-        "image_creation_threshold": 1,
+        # Disable automatic creation of image layers, as we will create them explicitly when we want them
+        "image_creation_threshold": 9999,
         "image_layer_creation_check_threshold": 0,
     }
 
@@ -225,7 +225,7 @@ def test_sharding_split_compaction(neon_env_builder: NeonEnvBuilder, failpoint:
 
     # Do a full image layer generation before splitting, so that when we compact after splitting
     # we should only see sizes decrease (from post-split drops/rewrites), not increase (from image layer generation)
-    env.get_tenant_pageserver(tenant_id).http_client().timeline_compact(
+    env.get_tenant_pageserver(tenant_id).http_client().timeline_checkpoint(
         tenant_id, timeline_id, force_image_layer_creation=True, wait_until_uploaded=True
     )
 
diff --git a/test_runner/regress/test_storage_scrubber.py b/test_runner/regress/test_storage_scrubber.py
index 7c411a6b84..a45430ca86 100644
--- a/test_runner/regress/test_storage_scrubber.py
+++ b/test_runner/regress/test_storage_scrubber.py
@@ -191,7 +191,9 @@ def test_scrubber_physical_gc_ancestors(
             "checkpoint_distance": f"{1024 * 1024}",
             "compaction_threshold": "1",
             "compaction_target_size": f"{1024 * 1024}",
-            "image_creation_threshold": "2",
+            # Disable automatic creation of image layers, as future image layers can result in layers in S3 that
+            # aren't referenced by children, earlier than the test expects such layers to exist
+            "image_creation_threshold": "9999",
             "image_layer_creation_check_threshold": "0",
             # Disable background compaction, we will do it explicitly
             "compaction_period": "0s",
@@ -241,7 +243,7 @@ def test_scrubber_physical_gc_ancestors(
     workload.churn_rows(100)
     for shard in shards:
         ps = env.get_tenant_pageserver(shard)
-        ps.http_client().timeline_compact(shard, timeline_id)
+        ps.http_client().timeline_compact(shard, timeline_id, force_image_layer_creation=True)
         ps.http_client().timeline_gc(shard, timeline_id, 0)
 
     # We will use a min_age_secs=1 threshold for deletion, let it pass