I have had the same bass for 15+ yrs, Cirrus USA. Love it, gets the job done.
I have had to replace tuners on it twice. One (D string) 5 yrs ago and another (B string) went out recently. They seem quality in general. Nice finish, great to the touch, nice ratio. Stays in tune better than any instrument I have owned.
Just curious if anyone has noticed similar lifespan on basses they have used a lot.
The only times I had to change a tuner was because of impact damage. Once on a bass I received that was badly packed and had a bent tuner, and another time when I stupidly rested a bass against my amp "it's just two seconds" and it fell (putting a nice little dent on the back of the neck too, although fortunately it got fixed with the damp cloth and iron trick).
It sounds like you've been unlucky, I can't imagine Peavey uses low quality hardware on that bass, that's a pretty nice bass.