Fluorocarbon leaders in the 40 to 50 lb range are the right call for abrasion resistance near wood, rocks, and dense grass
It also pairs with wire or heavy fluoro leaders for toothy fish
Oh so you want me to go study and observe insects, worms, crayfish, and minnows, to learn and then apply their size, color, breeding patterns, and migration habits to the particular lake Im fishing on this one free Saturday morning
This could be partly sentimental, as they harken back to the pre-synthetic era (before foam became a mainstay in the fly-fishing world.) But I think its also because of the more natural movement and breathability that deer hair provides
Experiment The approach Ive outlined is just a place to start