The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
I'd say 80% of the flies I now tie are thorax style with CDC upright wings, maybe 10% are tied somewhat down wing to imitate the emerger, and the rest are some parachutes and a few "Catskill style" just for old times sake.