I don't want to start an argument here, but that's a counsel of perfection. I have re-used Nylocs for many years and never had one loosen off. I would guess that as long as the thread is clean, it's possible (and safe) to use a Nyloc nut 5-6 times before it starts losing its grip. If it resists you when you are tightening it, it will resist loosening afterwards. I don't think I have ever used a Nyloc in a critical position like an axle or hub nut on a car or motorbike, and I would probably use a new one for this application. But for a bicycle axle I don't think I would be over-concerned. If it worries the OP, I would suggest spending a few quid on a large bag of them and carry a couple along with the patch kit.Nylocs.....but don't forget to use new ones every time you change....to work properly the nylon insert is one time use.
KudosDave