Lint in the bobbin area is cleaned at every bobbin change. That way it doesn't build up and make a problem.
Needles, ah well, sometimes I do forget to do that often enough, but usually you can tell when something is wrong.
rotary blades, as needed, when they do not cut properly, I change the blade. Also after I nick a pin (which usually happens 10 minutes AFTER I have just changed a blade) Sigh!