This idea of every PR being a small chunk that you can review in 5-10 minutes is completely ridiculous. It is reasonable for bug fixes or small improvements, but the review time you should expect for a PR should reflect the size and impact of a feature, not some arbitrary number.

Yes, everybody would love it if every PR was small enough. In reality that is not a good way to build substantial features.

Often, fully building out a substantial feature, causes you to change your mind and completely changing your approach the further along you are. You don't want to be muddying up the PR pipeline with a bunch of half-assed changes.

Doing that just makes reviewers less inclined to give good feedback on a PR, because they "know it's going to change so much anyways".

If you are building a substantial feature, it is reasonable that the PR is large and reviewers will have to dedicate substantial time to reviewing it. Reviewing it is work on its own and hopefully your engineers have dedicated time to review substantial features.

Of course, you should make sure your substantial feature is as minimal as possible, for whatever is needed to ship the feaure - but not any less than that.