Settle window
The wait after a change before judging it, so Amazon can finish attributing sales.
Amazon attributes a sale to the click that caused it, and shoppers do not buy immediately. Days one through three after a change look worse than reality because the spend has landed and some of the sales have not.
Judging inside that window is how good changes get reverted. The floor is three days and it is an Invariant — you can lengthen it, never shorten it below three.