We generally review anywhere from 50 to 300 lines per diff. An unfamiliar reader may not be able to anticipate spooky action at a distance in other parts of the codebase, but a good design doesn’t permit much of that anyway. The reader can certainly understand what’s going on in the change, and if they don’t they shouldn’t approve it.

Some of our changes are bigger if they touch several systems. You have to have very good knowledge of each system to make an assessment of the impact of the change. And nobody has time to really look into this. You don’t get much credit for code review on the scrum board.