Well, I'll keep this simple
I could go on a long story on this one. But, there is a big difference dmas. I'm not sure how many times you've fished here in the NW, but I fished the GL's with confidence and in "non crowded" conditions and had zero luck. But funny how instantly I had a hookup and kept catching fish when I switched over. I did not only fish in one spot mind you. I've made probably a good 50+ trips fishing the GL's throughout most of the GL states and rivers throughout (I have relatives strewn all over the area, but mostly in MN). Plus, the reverse is true. Some of those techniques would never work here, except in summer conditions (or drought conditions during winter). There is always a chance to catch fish on bigger flies anywhere. I've caught a small 12" rainbow swinging a size 2/0 "Hoh special" on the upper Hoh. So, there's always a chance. But, if I'm going to work a slot, especially remote, I'll use the most appropriate fly for the area. Now, skating flies. Well, depends on when you're talking about skating. If you're talking winter, then that's a much different beast all together if you constantly get them to rise in the winter time to dries. I've only met a couple (quite literally TWO) who have done this feat, and one was an over 20# steelhead at that. But for most part, you get alot of nose bumps, but no hits. During the summer, well, that's a different thing all together. But during the summer I use more naturals anyways, and SMALLER too. Most of the techs that I see used during the winter in the GL's were somewhat similar to what I see (and myself do as well) here in the NW for summerruns. So, we can agree to disagree. I've done most of my fishing in Ohio and MI, with some fishing in other states as well in the GL's. But I've found that my flyboxes were rendered useless the times I was there. At least, in the sizes I fished them at. Now, if I dropped down to maybe a size 6 or under, that may be different. But not up into my size 2 up flies.
Lastly, leeches are a different beast too. Can't bring those up. Most rivers (including our coastal glacial fed ones here ) have leeches in them. They are a food source, and well be fed upon. I've used some big assed leeches fishing for trout in New Jersey on the Penn. border. 3-4" for small browns and brook trout. So, that's a different beast. They'll open up and eat those readily. So leeches can't be accounted for in the "size mix" since it's an actual food source of real size (have seen leeches that big, if not bigger).
But, we can agree to disagree. You've fished them longer (like I said, I've only made about 50 or so fishing trips to the GL). But am basing off what I've seen and what has put fish on the bank for me. Since you yourself said that the flies you're using won't put the double digits on, which I assume you meant as just catching alot period. I assume the person above was looking for most productive flies. Especially if they are new to the sport. You want to give them the best opportunity to catch, not what has caught for you, but in limitated circumstances. I know I had quite a few high fish days, almost doubles using the smaller flies. And I'm someone who only came there during the weekends during fishing season for a few years. Figured, his best bet then beating the water with a bigger fly and only getting the few select. Always best to put someone new into a more productive atmosphere first, then let them go the way they want after that. If they want to try swinging bigger NW style flies, then that's their call afterwards.