Mario
I get a good long run from most of my flints, But being a Yankee most of my life (only been in the south for 15 year) I never throw anything away till it be plum wore out. That includes flints. If you get 30-40 shots on a flint now with a little sharpening on that you can get to do that again conservatively speaking 5 or 6 time over. It only takes seconds and you don't even take it out of the jaws unless it needs to be adjusted after knapping. Try it. You'll like it.
No brag, Just fact.