And, AFAIK, when that belt snaps, there are all sorts of problems for the engine that you can't fix with just installing the new belt.
Now, people will tell you that there are all sorts of problems building up in the camera if it isn't lubricated properly and that tens of different parts will be ruined, gears will be stripped in five years if space-tech-lubricants are not replaced every year or two, etc... But reality and Leica's (non-existent) service infrastructure will tell you this is probably another myth. As I said, this comes up often, myths are thrown around and when there is time to back them up... crickets.
I have a drum scanner and people will tell you (and user manual as well) that for proper operation and longevity you need to clean and lubricate parts with proper lubricants. Regularly! I do it. My car has a recommended oil change intervals and other periodic part replacements intervals. I do it. I send my Leicas or any other cameras for service if there is a problem. I've never been informed that any part needed replacement because of wear that could be prevented by spending crazy amounts of money for periodic CLAs.
I would do a check-up on a camera if I was a professional that absolutely needed a camera to work, though. But that’s not what we are talking about here…