I think it depends on how large your codebase is and how many dependencies it has. The first issue is that any new 3.x release is going to have bugs introduced

I think it depends on how large your codebase is and how many dependencies it has. The first issue is that any new 3.x release is going to have bugs introduced by new features, and possibly regressions in old ones. This could cause your current code to behave differently, as well as cause issues if someone immediately uses a new feature. The other issue is the more dependencies you have, the more likely one of them will not work with the newest version. Usually these things get sorted out pretty quickly, but it's frustrating to get a bunch of errors. I typically wait until at least the first bug fix release (3.11.1 for example) to try out a new Python version. These often have most of the common issues fixed, and give enough time for all the popular dependencies to catch up. This is from my experience maintaining a million+ line codebase that started at Python 2.6 and was updated to 3.8 as new versions came out.