Myth: more ad units = more revenue

Myth: more ad units = more revenue
The advice says "add another unit, stack the page." Density data says no. EPMV (earnings per thousand visitors, all ad income / sessions × 1000) by ad count, n=210 sites, 28d:

— 4 units $18.40 ▮▮▮▮▮▮▮▮▮
— 6 units $21.10 ▮▮▮▮▮▮▮▮▮▮▮
— 8 units $20.30 ▮▮▮▮▮▮▮▮▮▮
— 11 units $16.90 ▮▮▮▮▮▮▮▮

Past ~7 units, viewability and CPM both sag while bounce climbs. The 11-unit cohort earned less per visitor than the 4-unit one.

So what: session value beats unit count. Trim past 7. ▼8% EPMV in the overstacked tier.