Case: A/B testing 6 vs 12 header-bidding partners

Case: A/B testing 6 vs 12 header-bidding partners

What it did: split traffic 50/50 — control ran 12 Prebid bidders, variant trimmed to the 6 that won most auctions.

— Setup effort: 4/5 (Prebid config + GAM A/B by key-value)
— Outcome: 6-bidder variant matched RPM within 1.1% ($13.05 vs $13.20) but cut auction latency 380ms → 210ms
— Faster auctions raised timeout win-rate, and LCP improved enough to recover the tiny RPM gap

Pros: leaner stack, faster page, near-identical revenue, lower wrapper risk.
Cons: those 6 dominant bidders shift over months — re-run the test quarterly or you ossify.

Lift: ★★★☆☆ — Risk: ★★☆☆☆
Verdict: more bidders is not more money past a point. Trim and re-test. Best for: bloated Prebid stacks. Skip if you run under 6 already.