Playbook: Build a no-fill passback chain

Playbook: Build a no-fill passback chain
What it does: routes unsold impressions to a backup network instead of showing blank space.

Setup (effort 4/5):
— Order the chain by historical CPM: highest-paying demand first, house ads / affiliate last.
— Set a render timeout per tier (~1.5s) so a slow passback doesn't leave the slot blank.
— End the chain with a guaranteed fill — house promo or an affiliate creative — never an empty div.
— Tag each tier so you can see what % of impressions reach the bottom (your true no-fill rate).
— Re-order monthly; tier CPMs drift.

RPM lift seen: +3-8% by monetizing impressions that were earning zero.

Pros: recovers dead inventory. Cons: each tier adds latency; deep chains hurt LCP.

Lift: ★★★☆☆ — Risk: ★★☆☆☆
Best for: sites with 10%+ no-fill on direct demand. Skip if your fill is near 100%.