It's true, some clarity in the water does increase my confidence. But I'm amazed at how well fish see in turbid water. I've caught them with only 10" visibility at times. I figured out a few years ago that the main reason I prefer 3 or 4' of clarity is because it's so much easier wading when I can see where I'm putting my feet. Doing the Braille shuffle over and between the stones makes for a laborious day of stream wading. All that said, the best fish of the day came downriver where the water lost a foot or more of visibility than where we began. If I ever figure out this steelhead game, I'll be sure to write a book.
Another thing I learned when I fished lots more. In winter conditions, high turbid water, was to "short line". I fished w/ a fly rod and reel w/ mono, eggs or shrimp for bait. With only 4-8" water visibility, would work a gravel bar top to bottom, w/ only 10-15' line out of the reel, fixed. Didn't need a strip basket w/ such little line to work with. Cast, 2 steps, cast, 2 steps, etc. caught lots of fish when everyone else thought the river was out, sometimes in a foot of water. Fish would be laying in close. Transitioned that philosophy to the swing with little success so far. Wish I was swinging a fly back then, with lots more fish around. I would like to read your book.