"Stover nut" type all metal locking nuts are really only a one time use for both the bolt and the nut. If the bolt threads aren't mangled too badly they can be re-used, but there is the likely situation that the prevailing torque has been reduced so the retaining force will be too. I nearly always assemble them with the briefest smear of anti-seize to allow for an easier time in dis-assembly. If the bolt is "mission critical", meaning lives are potentially at stake, then I skip the anti-seize and consider the bolt and nut to be consumables.
Jet nuts and K-nuts seem to be re-useable since those designs are used in captured applications, but I'll defer to those with direct experience with them.
Elastic stop nuts (nylox) can be re-used until the retaining force is unacceptably low (spin on by hand?).
Common stainless bolts are Grade 2 or worse in strength (I consider them to be "Grade Zero"). Pretty and fine for holding on cowlings, shields, guards, etc., but have no application in structural loadings. If you need high strength stainless bolts I'll suggest consulting the ARP fasteners page.
I'm not so sure that prevailing torque, or Stover, or distorted thread all metal locknuts are one-time use only. According to Carroll Smith (via Wikipedia, Smith, Carroll (1990), Carroll Smith's Nuts, Bolts, Fasteners, and Plumbing Handbook, MotorBooks/MBI Publishing Company, ISBN 0-87938-406-9.), the elastic nature of the single distorted thread means that when it is removed it regains its original distorted form, meaning it can be re-used quite a few times.
A problem may arise when a Grade C or Grade 8 Stover type distorted prevailing torque lock nut is used on a soft metal bolt, say Grade 2 or not rated. Then the nut may distort the bolt threads, ruining the bolt. Since most automotive fasteners these days are Grade 8, I don't see this a problem with car/truck work.
My '67 Chevy Van came with prevailing torque conical top thread lock nuts on the leaf spring shackles (7/16-20). When I serviced the bushings (lots of croaking and squeaking) I replaced the stock shackles with new ones and new bolts. I used Nylon insert lock nuts, and lo and behold after a few miles the nuts loosened up. There was another problem, in that the replacement bolts had shoulders that were a bit shorter than the stock bolts, but I was still able to get 50 lbs of torque on them. Another issue was that the replacement new shackles were about 1/8" to 1/4" shorter than the original ones, and they resulted in the spring eye hitting the frame boss. Not so good. Also the shorter bolt shoulders meant that the bushings were getting quite squeezed, beyond what must have been their design parameters. To cut to the chase, I cleaned, lubed, and reinstalled the original shackles and bolts, with new prevailing torque locknuts. The springs are quiet now and the nuts don't loosen, even after several rounds of assembly/disassembly.
Originally I found this thread because a nut on the flange holding the exhaust piping to the header had come off completely (I noticed this while doing the suspension work). All the nuts were grade 8 with lock washers. I decided that the lock washers perhaps were not holding up to the heat too well, and decided to switch to prevailing torque lock nuts in this application. But I also wanted to check the boards to see if there are any concerns with that plan. I will use some anti-seize (still have the good old lead stuff too). The application is far enough away from the head that I don't think extreme heat will be an issue, though, as it is sometimes with exhaust studs installed directly on the head.
Bottom line is that I believe that if the bolt and nut grades are matched, the prevailing torque lock nut can be re-used.
