Tune ad refresh without killing fill

Tune ad refresh without killing fill
Ad refresh (reloading a unit after N seconds in view) adds impressions, but too-fast refresh burns advertiser trust and clearing prices. Sweet spot: 30-35s viewable refresh (n=66 sites).

— Step 1: Refresh only viewable units, and only after they've been seen.
— Step 2: Start at 35s, cap at 4 refreshes per session per unit.
— Step 3: Exclude the top unit from refresh (protects CPM).
— Step 4: Watch CPM per refreshed impression vs first — expect ▼ 20-30%, that's fine if net RPM rises.
— Step 5: Cut interval to 30s only if CPM holds.

So what: 35s viewable refresh nets ▲ 10-15% RPM at flat CPM.