Having multiple reviewers is often bad . A diffusion of responsibility means no responsibility. If you have three reviewers, no one feels personally responsible for checking it line by line and thinking about the code in depth. Instead a cursory glance seems acceptable, because, after all, other people are looking at it.
I’ve lived in a lot of collective houses. I’ve seen a lot of chore systems come and go. What I’ve decided is that it’s folly to try to enforce accountability. A good system provides visibility, that’s it. Who did what? Document it, but allow implicit social process to handle enforcement. Hard rules just lead to people cooking the books, or opting out of the system entirely. I feel the same about code review. Document…
Companies have managers. It's very important that mangers at a company set the tone for using mistakes to create better engineering processes. And that involves a lot more than shaming the committer.