diff --git a/backend/address2UPRN/tests/test_csv.py b/backend/address2UPRN/tests/test_csv.py
index 73d94388..5c97e691 100644
--- a/backend/address2UPRN/tests/test_csv.py
+++ b/backend/address2UPRN/tests/test_csv.py
@@ -12,12 +12,21 @@ FIXTURE_PATH = Path(__file__).parent / "test_data.csv"
 # Each parametrized case fires at least one EPC request; without throttling,
 # GitHub-hosted runners burst fast enough to hit 429s.
 EPC_THROTTLE_SECONDS = 1.0
+EPC_LONG_PAUSE_EVERY = 100
+EPC_LONG_PAUSE_SECONDS = 5.0
+
+_epc_request_count = 0
 
 
 @pytest.fixture(autouse=True)
 def _throttle_epc_requests():
+    global _epc_request_count
     yield
-    time.sleep(EPC_THROTTLE_SECONDS)
+    _epc_request_count += 1
+    if _epc_request_count % EPC_LONG_PAUSE_EVERY == 0:
+        time.sleep(EPC_LONG_PAUSE_SECONDS)
+    else:
+        time.sleep(EPC_THROTTLE_SECONDS)
 
 
 def load_test_cases():