I get to a favorite pool on one of my favorite river. First thing I do is check any insect activity with a pair of low power field glasses. I see several different flies on the water but only an occasional rise.
I get down to the river, wade out to where I want to start fishing, check the insects on the water again and try to catch one being taken. I think I know. I attach a fly, make a dozen casts, bring it in and tie on the same fly but a size smaller. Still no luck. I watch the surface again. A few spinners on the water but don't see any clouds of them when I look up. I try one anyway. Another dozen casts..No luck. I try an emerger and get one smallish fish. Cast it over and over and get no further action. I'll often wait 5 or 10 minutes to give the surface a break. Still not many rises even though I know there are many fish here and they should be looking up.. I try a different may fly that I see on the water. No luck. I try an ant...get another 10 inch fish...can't raise another. I go under water. Wet fly and a soft hackle, Then a bead head tiny pheasant tail. Nothing. I see a few more rises and switch back to dries. This requires some leader building and helps rests the water. They are rising like crazy now...Still several dif caddis and mayflies on the surface. I watch again to see which they are taking. There seems to be no rhyme of reason. They seem to switch every few minutes...
OKAY, now it is you in the same circumstances... hardly any rises at first... later, a few, and finally quite afew rises..but the trout are not concentrating for any length of time on any particular insect... How long to you fish one pattern with out success or with minimum success B4 changing flies...OR do you continue to beat the water with the same fly hoping that they will come back to what it is supposed to represent again...