1. For the most part, fish aren't all that smart.
2. Fish take flies for at least two reasons -
a. It looks good to eat
b. It acts good to eat
Alot of folks focus on 2a. They tend to carry alot of different fly patterns, If one fly doesn't work, try another.
Some folks focus on 2b. They carry very few patterns. The patterns they carry are very generic, the flies look like alot of things. They believe it's not so much the pattern you are fishing, it's how you fish it. If one presentation doesn't work, they try another (dead drift, skate, twitch, swing, dapple, float it, sink it etc)
Both schools of though work (primarily because of rule #1)
