it's up to you. the more helical the faster the arrow will stabilize, but the more drag you will induce. how far do you want to shoot? i've found no difference in feathers vs blazer vanes out to about 45 yds, both helical, but after that the poi on the feathers starts dropping compared to the blazers. feathers are also noticably louder. i'm not sure how many degrees i use, but i usually do as much helical as i can with the shafts i use. you'll find that using skinny carbon arrows, at a certain point, probably before 11 degrees, you won't be able to get the feather to seat properly on the arrow. if you're going to be doing it yourself do some testing.