My record is 22 patches before the stem pulled out. All through a continental 4000 23mm tire.
When I was a kid, I lived pretty far out from civilization, so getting new tubes was pretty rare.
For a while I was doing organized rides! with "serious" roadies, who were flinging their flatted tubes away when changing a flat. I picked up several, all higher dollar tubes than I buy, and I think I still have a few.
Right now almost all of the spares in every seat bag has a couple patches, I won't dig into the "new" drawer unless I have to.
Interestingly, I once offered a tube to a guy on a ride who was out, he refused it as it had a couple of patches
