Not all CDC is created equally. I understand Jeremy Lucas dressed the original with one oversized feather on a size 14 hook, and it works! With average CDC I would use no more than 3 "normal" feathers on a fine wire hook of that size .The whole point of the fly a gentle presentation and footprint, do not overdress! Try it, it's amazing if you can cast properly with a long leader and fine tipped how easily these flies float.How many plumes should I include on say a size 16 plume tip?
I have seen suggestions from 2 to 5.
Would value some views.