This is not a direct answer to your question, but might be relevant nonetheless. What I have learned is that having automated tools that enforce your code styl

This is not a direct answer to your question, but might be relevant nonetheless. What I have learned is that having automated tools that enforce your code style and measure code quality (e.g. Code Climate, rubocop in the Ruby world, jshint etc.), integrated in your test suite or CI, goes a long way in improving the quality of your PRs (and, of course, code in general). There's a cognitive difference between reading a code review written by a colleague and having a set of rules that are simply enforced automatically. This might matter a lot for new hires who have yet to learn that code reviews are about getting better and learning new things (and not about highlighting mistakes). Of course this wont replace code reviews, but it might remove some friction.