An interesting discussion can usually be started by introducing the differing views held by anglers regarding the importance of pattern when considering the relative importance of proper presentation.
Myself, being limited in time to tie every possible pattern and carry them in various sizes and color variations, I tend to emphasize presentation over pattern. I have observed wild rainbow trout in Mills Lake up in RMNP feasting on bits of bagel some German tourists were feeding them. This kind of makes “match the hatch” a problematic consideration at best.
While there is no question that fish become accustomed to feeding on a particular size insect during a particular hatch event, rarely will one pass up the large dose of nutrition that a grasshopper fly offers.
A lot of lethargic trout can be encouraged to strike with a little motion of the fly when the dead drift offering passes by unnoticed. Perhaps this is a reaction strike with nutrition second to aggression and the desire to kill. Any way you see it, it amounts to a presentation situation.
I have often thought that a skilled presentation can entice even a reluctant trout to strike a fly that may not “match the hatch”. So, my advice is save yourself the time of tying or the financial investment buying one of every pattern in the book or fly shop, and concentrate on a few “go to” flies instead, and focus more on presentation than pattern. Most of the pattern advocates I know spend a lot more time trying different flies and tying on tippet than they do fishing which is why, using only a couple of patterns, I can usually out fish them. I guess this is the basic concept behind the “one fly” tournaments.
Les A. Beery