for the very most part, feather shape don't matter much. total fletch surface area do, along with the amount spin you add via feather offset or helical.
i like a lotta shaft rotation to get the arra to spin quick off the shelf and help me with a bad form release, and that takes some good fletch surface area and offset/helical.
if i hadda have just one fletch shape/size, it'd be a 5.25" high shield with maximum helical.
it pays to do some fletch testing
with your choice of broadheads, and not just field points. that's where the rubber meets the road for trad bowhunter, i'd think.