That’s not true unless you have a dependency map between all modules. (Note: that’s what I did in pytest-fastest to only retest modules that had changed, or that imported modules that had changed.) Otherwise, if you rename a function, you wouldn’t know what all broke.

You don’t need to check everything, every time. (Another case of yours is when you want all types checked.)

Good time for a full check is when new feature is complete. Run all linters, typers, and full test suite, until clear. Then commit and push.