Time-based refresh vs activity-based refresh

Time-based refresh vs activity-based refresh

What it does — both reload ad creatives to bill more impressions per session. Time-based fires every N seconds; activity-based fires only on user action (scroll, tab focus, click).

Setup effort (1-5) — Time: 2 (one interval). Activity: 4 (event listeners, viewability gate, focus checks).

RPM lift seen — Time-based at 30s: +20-35% impressions but viewability craters and eCPM drops ~15%. Activity-based: +10-18% impressions with viewability intact, so net RPM often wins.

Pros / Cons —
Time: dead simple, but refreshes off-screen units and buyers notice (re-bid suppression).
Activity: protects viewability and eCPM, but more code and lower raw count.

Verdict — Use activity-based with a 30s floor and in-view requirement. Pure time-based only on a slow-scroll long-read where dwell is genuinely high.

Lift: ★★★★☆ — Risk: ★★★☆☆
Best for: content sites with 90s+ dwell. Skip time-based if your eCPM is already premium-buyer driven.