Comment by JohnBooty
4 years ago
They last longer if you wear them, say, several times a month - i.e. if you have a rotation with several quartz watches and several mechanical ones. They definitely will last decades that way.
As others have noted, if you own a well-known brand like a Seiko you can easily purchase an entirely new movement for $50-$75 and this should take a watchmaker no more than one hour of labor or you can DIY. (Many non-Seiko brands use NH35/36 movements, which are made by Seiko)
Will Seiko provide parts for older watches? I just got stuck with a bricked Swiss Army quartz watch because no one can get parts for it (it's 20 years old). I'm very tempted by some of the more affordable Seiko mechanical/automatic models, but I'd like the watch to last at least a decade or so.
Sadly, I'm not aware of any specific "we will continue to manufacture parts for X years" guarantees from Seiko.
Still, though - keep in mind that entire Seiko movement can be bought for like $50-75. And many of their most common movements are interchangeable. For example, an older 7S26 can be replaced with a new NH36 that sells for about $50. https://chronometercheck.com/seiko-7s26-movement/
It's not entirely unfeasible to imagine buying a spare movement or three if you were, say, planning on doing sort of a heirloom thing and wanted to ensure a supply of parts N decades into the future.