When do you switch flies/spots?

After fishing yesterday and going through only 3 flies the whole day and getting a mixed bag of results I was wondering how often you change them. I also changed spots only twice which came out so-so. I'm always hoping to hone in on that perfect fly and perfect place but never really know when to change. This has got to be probably the most difficult part of fishing for me.

So do you go through a lot of flies until something works? How many casts, how long, do you go until you figure it's not working? Is there a fly that you use that works almost all the time? What is this "go to" fly?

This is pretty much the same for conventional fishing so anyone feel free to reply w/ their routine.
Thanks.

Z

Good questions, Zee.

The fish question is easier, I think, so will start with that. My general rule is to not leave fish to find fish. (Got to find them, first.) Of course there are exceptions, especially if I think I've burned out the group I've been working over, and I'm sure there are fish elsewhere.

For flies/lures- I usually have a few that I'm most confident about, based upon experience/history/research. I'll stick with those 2-3 selections until I'm sure that they been rejected by lot's of fish. If I'm not sure the fish are around, I'll stick with those flies. I'll only change flies when I'm sure that what I'm using is not the right fly. I usually start with the smallest, least obnoxious fly (especially when the water is clear, and the fish easily spooked), and work my way up to the big bright birds.