I carried some flints with leather glued to them in my possibles for years & never used them. When I
hunt I put a new flint in, no way I will wear it out as I get 40-100 shots from a good flint in a good lock.
I may knap it a couple times but I use it til it is dead. However, I did lose a flint one time. Got to the knoll I wanted to hunt from, looked at the rifle lock & flint was gone. But I always have 2-3 flints & 2-3 leathers in a pouch in possibles. I use old shoes & boot leather to make mine. Kinda picky on the thickness too.