After any applied change, the campaign enters a cooldown - a window during which no further changes are allowed, so Smart Bidding can stabilise before being judged or changed again.
Budget adjust, under $500/day - 7 days. Smaller campaigns stabilise faster.
Budget adjust, $500/day and over - 14 days. Larger campaigns need more time.
Target adjust (tCPA/tROAS value) - 14 days. Target changes ripple through bid calculations.
Bidding strategy switch - 21 days. A full strategy change is the most disruptive thing you can do to a campaign.
Learning-phase campaigns (under 30 conversions) - 14 days minimum on any change.
Two rules govern them:
The longest applicable window wins - a strategy switch on a learning-phase campaign waits the full 21 days.
Cooldowns are per campaign - a cooldown on Campaign A never blocks changes on Campaign B.
And the one-lever rule extends through cooldowns: after a bidding change, the budget lever on that campaign is also blocked until the window expires, and vice versa.
RELATED ARTICLES
One lever at a time
Bid and budget are never touched together - by design.
Account throttle & cadence
The two account-level speed limits.
Reverting a change
Every applied change has a road back.