Reviewing code is one of the responsibilities of a software engineer. It helps unblock other people, and is thus crucial to a team’s velocity.
Review at least daily. This mirrors Google’s guidelines on code review speed:
If you are not in the middle of a focused task, you should do a code review shortly after it comes in. One business day is the maximum time it should take to respond to a code review request (i.e. first thing the next morning). Following these guidelines means that a typical CL should get multiple rounds of review (if needed) within a single day.
Some engineers will argue that doing code review interrupts their flow, but flow does not persist overnight nor over lunch. Additionally, even though flow is important, it should not make the team’s velocity suffer.
Given that fast review cycles benefit team velocity, it makes sense for fast reviews to be rewarded, perhaps by taking it into account in the feedback/promotion process.
Junior engineers are not exempt from code reviews. Senior engineers can still learn from junior engineers, and code reviews is a good tool for this.
As a team lead or senior/staff engineer, lead by example and review quickly.