Some of the most notable 35mm photographers burned through rolls, you can see it in their contact sheets. Rarely do you see more than two or more amazing pictures on a roll. I dont think you can judge someone on how good they are by the number of shots they take, it should be the end result that should be judged, be it a high or low ratio of keepers. And then even that, the act of judging an image is so subjective, one generation may hate it, another may love it, depending on societal perceptions at that point in time.
Personally, I don't take more than 1-3 shots of a subject most of the time. You do get wrapped up sometimes and I'd just rattle off a bunch, but mostly just 1-3. I trust in myself that I would have captured what I wanted in those.