Voice of customer
Frequency capping
One survey per session across everything you run, and answered once means never asked again.
The global cap is the important one. At most one survey is shown per session across every survey you are running, not one per survey. Two widgets in one visit is how you teach people to dismiss on sight, and that damage is permanent across every survey you will ever run.
Within a single survey there are three further rules. Somebody who answered is never asked that question again, with no re-ask window at all by design. Somebody who dismissed it is held off for a cooldown you set, thirty days by default. And there is a maximum number of prompts, two by default, after which they are left alone whatever the cooldown says.
The whole thing fails closed. If the browser cannot tell whether somebody has been asked before, because storage is unavailable or blocked, nothing is shown. Failing the other way would mean surveying every private-browsing visitor on every visit, which is the worst possible version of this feature.
The record is pruned as surveys end, so a long-lived visitor does not accumulate entries for surveys that finished a year ago.