The only spare parts I collect are magazines for my rifles and pistols. When I finish school I would like to start purchasing them and also learn some basic gun smithing: such as replacing extractors and other worn out parts.
I mean, I have the original parts if my apex dcaek takes a dump. I don’t keep extra strikers, firing pins, guide rods, etc on hand. I haven’t had any failures I couldn’t fix with over night shipping and if shtf, I’d have several firearms on me.
I'm in this camp. I tried finding a simple recoil spring for one of my 1911's during the height of the panic and came up empty. Never again. Any time I see Chuck Schumer or Nancy Pelosi, I automatically place an order for extra magazines and parts.
For me, it depends on how old the firearm is. For my C&R things, enough seems to be never enough.
And I think I'm going to stop buying AR parts since they just turn into builds. And, oddly enough I've got enough of those.
But the newer firearms, well, I tend to acquire parts for them as needed. And I don't really have a cut-off for newer vs older.