They're sold as a cheap substitute for rare/illegal feathers used in spey flies. But spey flies are not the best fish catching patterns so I use them in several different colours for nice wings on mini-muddlers or wing cases/tails for nymphs, etc. You can even make a "Pheasant Rump Nymph" so yes, don't be afraid to veer from any recipe since keeping to a recipe generally doesn't matter. Catching fish is 90% fishing skills, 5% fly fishing specific technique, and 5% fly pattern.