diff --git a/cloudinit/config/modules.py b/cloudinit/config/modules.py
index ab3a0e130a2..efb7a5a4343 100644
--- a/cloudinit/config/modules.py
+++ b/cloudinit/config/modules.py
@@ -172,7 +172,8 @@ def _fixup_modules(self, raw_mods) -> List[ModuleDetails]:
                     raw_name,
                     freq,
                 )
-                # Reset it so when ran it will get set to a known value
+                # Misconfigured in /etc/cloud/cloud.cfg. Reset so cc_* module
+                # default meta attribute "frequency" value is used.
                 freq = None
             mod_locs, looked_locs = importer.find_module(
                 mod_name, ["", type_utils.obj_name(config)], ["handle"]
@@ -186,6 +187,9 @@ def _fixup_modules(self, raw_mods) -> List[ModuleDetails]:
                 continue
             mod = importer.import_module(mod_locs[0])
             validate_module(mod, raw_name)
+            if freq is None:
+                # Use cc_* module default setting since no cloud.cfg overrides
+                freq = mod.meta["frequency"]
             mostly_mods.append(
                 ModuleDetails(
                     module=mod,
diff --git a/tests/integration_tests/modules/test_combined.py b/tests/integration_tests/modules/test_combined.py
index eb45062eff2..70850fd9038 100644
--- a/tests/integration_tests/modules/test_combined.py
+++ b/tests/integration_tests/modules/test_combined.py
@@ -5,12 +5,16 @@
 the same instance launch. Most independent module coherence tests can go
 here.
 """
+import glob
+import importlib
 import json
 import re
 import uuid
+from pathlib import Path
 
 import pytest
 
+import cloudinit.config
 from tests.integration_tests.clouds import ImageSpecification
 from tests.integration_tests.decorators import retry
 from tests.integration_tests.instances import IntegrationInstance
@@ -223,6 +227,26 @@ def test_cloud_id_file_symlink(self, class_client: IntegrationInstance):
             class_client.execute("stat -c %N /run/cloud-init/cloud-id")
         )
 
+    def test_run_frequency(self, class_client: IntegrationInstance):
+        log = class_client.read_from_file("/var/log/cloud-init.log")
+        config_dir = Path(cloudinit.config.__file__).parent
+        module_paths = glob.glob(str(config_dir / "cc*.py"))
+        module_names = [Path(x).stem for x in module_paths]
+        found_count = 0
+        for name in module_names:
+            mod = importlib.import_module(f"cloudinit.config.{name}")
+            frequency = mod.meta["frequency"]
+            # cc_ gets replaced with config- in logs
+            log_name = name.replace("cc_", "config-")
+            # Some modules have been filtered out in /etc/cloud/cloud.cfg,
+            if f"running {log_name}" in log:
+                found_count += 1  # Ensure we're matching on the right text
+                assert f"running {log_name} with frequency {frequency}" in log
+        assert (
+            found_count > 10
+        ), "Not enough modules found in log. Did the log message change?"
+        assert "with frequency None" not in log
+
     def _check_common_metadata(self, data):
         assert data["base64_encoded_keys"] == []
         assert data["merged_cfg"] == "redacted for non-root user"
diff --git a/tests/integration_tests/modules/test_frequency_override.py b/tests/integration_tests/modules/test_frequency_override.py
new file mode 100644
index 00000000000..0cefadcc574
--- /dev/null
+++ b/tests/integration_tests/modules/test_frequency_override.py
@@ -0,0 +1,33 @@
+import pytest
+
+from tests.integration_tests.instances import IntegrationInstance
+
+USER_DATA = """\
+#cloud-config
+runcmd:
+ - echo "hi" >> /var/tmp/hi
+"""
+
+
+@pytest.mark.user_data(USER_DATA)
+def test_frequency_override(client: IntegrationInstance):
+    # Some pre-checks
+    assert (
+        "running config-scripts-user with frequency once-per-instance"
+        in client.read_from_file("/var/log/cloud-init.log")
+    )
+    assert client.read_from_file("/var/tmp/hi").strip().count("hi") == 1
+
+    # Change frequency of scripts-user to always
+    config = client.read_from_file("/etc/cloud/cloud.cfg")
+    new_config = config.replace("- scripts-user", "- [ scripts-user, always ]")
+    client.write_to_file("/etc/cloud/cloud.cfg", new_config)
+
+    client.restart()
+
+    # Ensure the script was run again
+    assert (
+        "running config-scripts-user with frequency always"
+        in client.read_from_file("/var/log/cloud-init.log")
+    )
+    assert client.read_from_file("/var/tmp/hi").strip().count("hi") == 2
diff --git a/tests/integration_tests/modules/test_write_files.py b/tests/integration_tests/modules/test_write_files.py
index 1eb7e9454cf..a713b9c5cf2 100644
--- a/tests/integration_tests/modules/test_write_files.py
+++ b/tests/integration_tests/modules/test_write_files.py
@@ -50,6 +50,7 @@
     defer: true
     owner: 'myuser'
     permissions: '0644'
+    append: true
 """.format(
     B64_CONTENT.decode("ascii")
 )
@@ -91,3 +92,8 @@ def test_write_files_deferred(self, class_client):
             class_client.execute('stat -c "%U %a" /home/testuser/my-file')
             == "myuser 644"
         )
+        # Assert write_files per-instance is honored and run only once.
+        # Given append: true multiple runs across would append new content.
+        class_client.restart()
+        out = class_client.read_from_file("/home/testuser/my-file")
+        assert "echo 'hello world!'" == out