How often should I polish my car?
You shouldn't polish your car if you have had a paintwork protection coating. There is no need to apply any product over a ceramic, graphene, diamond or polymer coatings, especially not a polish.
A Polish is an abrasive product designed to removed oxidized paint. Your coating should not oxidize, and using a polish can only diminish the coating. If you see signs that your car needs a polish, you should take it back to where you got the coating applied, so they can diagnose the problem.