OM- I do not need many flies because I have such trouble tying them on the line (poor eyesight) that I never change it until it somehow goes missing. I throw the same old thing at every fish and it does not seem to matter. I caught the biggest fish ever (+20 inch Yellowstone Cutthroat) on a ratty fly that barely had a thread covering the hook!

Very annoying when I loose a new fly on the first cast because I tied it on wrong. Or the first fish runs off with it for the same reason.