diff --git a/src/scheduler.js b/src/scheduler.js
index 8ad2eba..10f49b9 100644
--- a/src/scheduler.js
+++ b/src/scheduler.js
@@ -98,7 +98,8 @@ function startScheduler() {
 
       try {
         const concurrency = Number(config.contentBackfill?.concurrency) || 5;
-        await backfillMissingContent(-1, concurrency);
+        const perSource = Number(config.contentBackfill?.perSource) || 50;
+        await backfillMissingContent(perSource, concurrency);
       } catch (error) {
         console.error('content backfill failed:', error);
       }