Well put Bob. You made a point that I have really never thought of.
I am the same with parachute patterns. I stopped tying them years ago in any quantity because I've never had luck with them. But admittedly I would go to the one pattern I still tie just in case, (a Parachute Adams, because they are supposed to work....right?) but in those same settings you just described. And like you said, I had already proven the fish were tough that day, so why should I expect that fly to do any better?
Great point!