I work at a small organization where code reviews are good, but 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.

Here’s another: most code reviews on larger companies are BS, just for show and nitpicking.

Story time.

Once I worked with a developer that just joined the company straight out of college, and had far more ambition than competency. That developer decided that code reviews where the venue where their high bar for code quality would shine, so they decided to nitpick everything that went against their poorly formed sense of taste. As luck would have it, the developer was assigned to a legacy project that was in cold storage for years and had no tests and linters, and was in a really poor state, and proceeded to leverage that to challenge each and every insignificant detail such as if a space should be at the left or at the right of a symbol. Each code review automatically received dozens of comments nitpicking whitespace changes. What a waste of time with so much noise.

I drop by the project, and noticed the churn that developer alone forced upon everyone, as that team had a rule that all code reviews should be passed by all reviewers and that reviewer made it their point to reject reviews that didn't complied to their opinion on whitespace. So the first thing I did was onboard a code formatter, and made it my point to subject the spec to an unanimous code review. That problematic developer made it their point to nitpick away each and every single setting, but it turned out some of their opinions conflicted with previous feedback.

So the code formatter tool was onboarded onto the team. Did that stopped the problematic developer from continuing their nitpicking? No. Except this time around other developers started pushing back because the opinions were contradictory and contrasted with the official code formatting style.

All it took was a couple of days for the problematic developer to go from dozens of comments per day to zero. The code formatter was still optional and not fully adopted, but the problematic developer simply ceased with the bickering.