Why we never judge a change after 7 days
Bidding algorithms need time to re-learn, and sales often arrive days after the click. Reacting too fast is one of the most expensive habits in paid media.
A new bid target goes live on Monday. By Friday, cost per conversion is up 20%. The instinct is to undo it. Most of the time, that's the wrong move.
Two things are happening at once
First, smart bidding needs time to adjust. After a significant change — a new target, a big budget shift, a new conversion action — Google's bidding goes through a learning period, typically around a week and longer for accounts with few conversions. Meta's ad sets do the same: they exit learning after roughly 50 optimisation events in a week.
Second, conversions lag. If customers usually buy two to five days after clicking, the most recent days always look worse than they'll end up. Last week's numbers will still grow.
How we handle it
- Write down what we expect a change to do before we make it, and when we'll judge it.
- Wait at least one full conversion cycle — usually two weeks — before calling a result.
- Avoid stacking changes on the same campaign, so we know which one did what.
- Watch daily for things that are actually broken (tracking, spend spikes, disapprovals) — those don't wait.
This is exactly why we report every two weeks. One week is often noise. Two weeks is enough to see what a change really did.
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