Comment by squirrellous

One pattern I've seen is that a team with a decently complex codebase will have 2-3 senior people who have all of the necessary context and expertise to review PRs in that codebase. They also assign projects to other team members. All other team members submit PRs to them for review. Their review queue builds up easily and average review time tanks.

Not saying this is a good situation, but it's quite easy to run into it.