The purpose of code review is not to find defects

Code reviews are inadequate at finding bugs.

If code reviews were good at finding bugs, then codebases that require two or more code reviews would be the better codebases. In practice, the opposite is more likely to be true.

Better approaches to finding defects include manual QA, and automated testing (preferably good end-to-end test coverage).

References

Czerwonka, Jacek, and Michaela Greiler. 2015. “Code Reviews Do Not Find Bugs. How the Current Code Review Best Practice Slows Us Down.” In . IEEE - Institute of Electrical and Electronics Engineers. https://www.microsoft.com/en-us/research/publication/code-reviews-do-not-find-bugs-how-the-current-code-review-best-practice-slows-us-down/.