Just don't use a skated caddis imitation when the spotted sedge is out on the Missouri, Big Hole, Big Horn, Yellowstone, Bitterroot, Blackfoot, or Clark's Fork rivers. For if one does use a skated imitation of a spotted sedge on these (and many other rivers such as the upper Delaware in New York and Pennsylvania, or even the Yakima) rivers one may be surprised by the number of trout one will hook.
Naw. On second thought, one should never use a skated spotted sedge imitation every on any river because everyone knows that fish get spooked by drag and a skating fly has so much drag it isn't funny.
The first time I saw this work was the fist time I fished the Yakima. We were drifting and I tossed a Royal wolf under a tree into water slower than we were drifting, as drag set in and the fly was dragged out, a bug bow began chasing the fly slashing at it with abandon. It was quite exciting, to say the least.
I sort of fell into this a few years ago on Fish Lake near Cheney. Caught bass on dries as I was unintentionally skating them in. I switched to a very large Sofa Pillow (see attached) perhaps size 4 or 6. Caught several 12-14 inch brookies on that fly.
If a 12 inch brook trout will chase a skated fly that big I know it works. I'll skate what I have now from time to time and it definitely works for me. Dito on the Stimulators too.
During 10 of the 12 years I lived in Montana, I caught quite a few large trout (and had many truly huge ones break off 15lb tippets) below Holter Dam at night. None of them were ever hooked with a mouse though. All of them were hooked on large sculpin (as in 2/0 or 3/0) imitations or Zonkers fished with a type 4 sinking 30' shooting taper on a 9' or 10' 8 or 9 wt rod.