How many teams did you see?

On your original claim, I have seen engineers put up 5x more PRs simply because they paid less attention to the quality or put less thought on each one of them.

I have seen people put up 5x more quality PRs too. But as long as they follow the good practice of doing a code review for every PR they put up (or 2 if you require 2 per PR), they got their stuff through quickly as well.

> your process ought to catch both of those well before the PR stage

We have multiple points where mistakes of any sort can be caught, and code review is one of them.

Yes, most architectural issues should be caught earlier, but some will only become evident in code: some by the dev themselves, others by reviewers.

This is only a problem if you mostly catch architecture issues at code review phase.