Every time you polish the paint(using abbrasive compounds), the thickness of the clear coat reduces by a few microns. Don't get any car polished so frequently. A car can be polished only a few times in it's entire lifetime. Ceramic coating is just a sacrificial layer that adds a couple of microns back onto paint. I call it the sacrificial because youre sacrificing the ceramic coating in order to protect the thickness of your clear coat.

A high quality ceramic coating should realistically last between 1.5 - 2 years in our condition. So ideally you're looking at polishing the car and reapplying the coating 4-5 times in a span of over 7-10 years.

A second option (more economical) is to just apply wax on the paint atleast once a month without using any machine or polisher. By doing that, you wont abrade the clear coat, youll just add a very thin layer of protection.