I have spent so much more time watching the water and finding actual fishing lanes where Trout go to feed than actually fishing. Certainly prospecting is a way to go but I have never been a one to flog the water with "go to flies". My best tool is actually a small pair of binoculars to look for trout that are either rising or in many cases just finning on the bottom between hatches. Not all areas hold trout. There are literally dozens of different bugs that are available to Trout during the course of the year if you are a Dry fly fisher. Beginning with Midges, Stoneflies, Ants, Caddis and Tricos plus a host of others. Each has not only its season but its time of day and place on the river. Some are early morning or late evening in the dark so that all you hear is gulping trout to try to target with you casts.
From just a personal point of view I fish with the objective of getting to know the river, when and how the trout feed. I have kept a concise fishing diary of such things as water temperature, flow height, and bugs encountered on all the streams I fish, they are all different but the research is half the fun. I also take pictures of Mayflies and other bugs to have an idea what I am up against and need to tie or find a fly that matches. That is not to say that you can't fish any way you want but this is what makes sense and satisfies me. Maybe I'm just getting old and set in my ways but it's what gives me pleasure. I can fish Nymphs and do very well or swing a streamer and nail a big brown in a lie, but my goal has always been to fool a trout feeding on surface or slightly subsurface and catch trout on my terms. I cant count the hours it has taken me an to slowly get myself into position behind a rising fish and get that one or two drifts. Mind you I've blown enough stalks on trout but its part of the game.
Just my Old Guy two cents.