Code Review: What do you review in a peer code review?
All changes made should be reviewed in a code review; however, it is normal to focus in on key areas. It is okay for the author to give some hints at something he wants the reviewer to specifically focus on.
“We look at everything, but generally focus on the more interesting areas. What’s interesting? Whatever jumps out at us when we’re looking at the code, or anything the author specifically wants to focus on. Our goal isn’t necessarily to put a microscope to every single line of code.”
– Jeff Atwood