So I'm passing through Arcata CA in the late '90s and this guy is like, "Hey man, do you have any acid?" And it calls to mind a long-forgotten memory, so I'm like, "You know, I think there's a 5-strip somewhere in my car, from like a year and a half ago. I don't know if it's still any good, but if I find it, I'll split it with you." So I went back to my car.
It was still good. It was blotter stored in tinfoil, wrapped up in something else and stuffed somewhere. It came into contact with nothing absorbent. It was subjected to no light at all, and very little airflow (package was probably jostled a bit and the vibrations from the car driving), but definitely to the summer heat and a chilly humid Seattle winter, with seemingly little loss in potency.
There are so many urban legends about acid, but it definitely CAN stay good for a long time, if stored properly, or even just mostly avoiding the usual weathering mechanisms.
I'd probably get a contact high just trying to figure out a Buchla system, but I don't think I'd be tripping...