I bought a 12 year old focus several years ago with 50k on the clock original timing belt, sold it to a friend who put another 60k on it over the space of several years. He never had the belt changed.
He sold it back to me in 2021 cheap, so cheap I give it to my ex girlfriend who needed a car, anyway to cut a long story short she sold it last year with over 120k on the clock and I see it on Facebay a few months later with a suspected snapped belt!
The car was a 2005 model so the belt lasted well past its use by date and recommended mileage.
I've seen a few manufacturers giving two intervals lately I.e 80k warranty and 120k out of warranty.
Personally I've always done the belt on the cars I care about on mileage alone and not had a belt snap on me yet.
I think someone that uses their car alot is gonna hit the mileage long before the belt is considered out of date and those that don't use the car a lot don't do enough miles for the belt to be that badly degraded in the time frame.