Things like recoil springs and firing pins are pretty much a MUST for serious shooters because sometimes it’s not always the guns fault that something wears out or breaks.  Sometimes bad ammo can wear out a firing pin faster than normal and recoil springs are going to wear out at some point.   The 2nd recommendation I would have would be to store magazine springs and followers.   Those will wear out, not as often, but as often as recoil springs.   If you’re a plinker and occassion shooter, these won’t be necessary, but if you put a couple thousand rounds through your Glock every year, something is going to wear down at some point so it’s best to have the spare parts around when it happens.

Everyone know that Glocks are tough.   I shoot just about all of the popular semi-autos out there and I still have to admit that Glocks are one of the least likely to break.   I’ve seen slide stops break, barrels blow out and slides crack, but none of them were Glocks.   Sometimes it’s a good idea to have a few extra Glock Parts in your safe just incase you ever need them, but since Glocks don’t use very many parts, it’s not much to store.