As a reviewer... it really, really depends on how trivial or gnarly the PR is.

If it's a simple change that is obviously correct, I'll try to unblock the author ASAP - often within minutes, even if it interrupts my flow.

If it's a giant PR with lots of risky changes in vital code, an awkward-to-unreadable diff, and/or maddeningly questionable design/coding decisions that require me to think a lot and compose some nuanced, reasoned comments to steer you in a better direction, then, well, you might find yourself nagging me for a review 2 days later. (And I'll probably ask you to split up PRs like this in future, e.g. to separate major refactoring from any logic changes.)