I’ve noticed that the larger the code review, the faster it needs to get done in order to avoid merge conflicts, which means large code reviews are much less effective in proportion to the size.

Exactly. And in larger corporations where you have many people contributing and the code is moving fast, having people nitpick your PRs just for show is crap because it delays everything sometimes by days. I had to say no very clearly to some people on code reviews because they were demanding me to place variables in alphabetical order on hard PRs that took quite sometime to get working and were very prone to code conflicts.