I think they could do those things with small PRs if they chose. If their agents are not intelligent enough to make small prs, I guess they can YOLO and assume everything is just fine with what the agents did. I do think small PRs would be better for agent review as well though, because they avoid any problems with context being overwhelmed and things being missed/forgotten.

What are the PRs you're thinking of though. If you mean a full clean rewrite, they'd probably proceed with spec first then just write it in bits to the spec. No reason it has to be large prs or smaller that's a design choice.

Often an exercise I find useful is do a quick big PR, then split it into small chunks that make sense independently for review. Or you can chain prs. Both those things can be done.

You're welcome to do large PRs, I'm not a fan of huge PRs though and would not pretend to review them (as pretending is what it would be), nor would I like to work somewhere where this is the culture.