My rule of thumb is that if you have an OnCall rotation for a codebase, you should require reviews. Besides all the benefits you've mentioned, its important to spread know-how of the code so that people on the rotation don't need to be pulled in e.g. over the weekends/on vacation because they're the only ones familiar with the code.

(There should be breakglass mechanisms to bypass code reviews, sure. Just the default should always be to require reviews)