A first requirement for direct-to-main development is that you can be reasonably sure your code will not break the CI build otherwise you'll ensure perpetually

A first requirement for direct-to-main development is that you can be reasonably sure your code will not break the CI build otherwise you'll ensure perpetually broken builds and a process many times slower than PR:s. Because that’s what PRs are mostly: validation that they won’t break the build on main. Reviews aren’t strictly necessary but compiling is. In some small project you might be able to run compile/test as part of a commit hook but for a situation where builds might take several hours or the developer can’t test all platforms that CI will, then it’s only possible to keep a green main by validation. In that scenario reviews wouldn’t be the limiting factor either.