On my last scooter, I had never adjusted the exhaust valve more than once because it was extremely difficult to get to (underneath the engine, had to bend the feeler gauge which made it hard to tell if it fit or not, couldn't see what you were doing), and the consensus seemed to be that if there weren't any problems or weird noises, the valve clearance was fine.
Every time I've checked the valves on this one though, they've needed adjustment.
Since starting this thread, it also occurred to me that my last scooter did in fact have an oil filter... that I never changed because there wasn't enough clearance to fit a wrench in to turn the bolt (and possibly the consensus was that it was unnecessary).
I'm definitely grateful for how easy this scooter is to work on.
Unrelatedly, there's very little brain surgery going on here. My username has less to do with brain broccoli and more to do with fish.