I would say this is never healthy, even for a team of 2 people. These days merging code without at least asking for a review should be anathema for devs. Even a 'rubber stamping' review at least signifies a shared awareness of changes.
Other workflows exist; pretty silly to act like you’ve found the One True Way.
If you don't care about code reviews, why care about a PR process? don't protect the branch and just make your commits. The notion of a pull request is you're requesting someone pull in your changes. But you don't want them to review those changes?!