I fletch mine at 90°. I don't have to look at it, nock and broadhead tuning isn't an issue and I only have to buy one color of feather so I can save by buying in bulk (the savings of course are more than offset by having to buy four instead of three feathers) and besides just liking them and the sheer inertia of habit, I realize there aren't many other good reasons behind it. The 75/105s look like I screwed up my 90/90s, which happens. Even so, they fly just as well.
I tried 3" but couldn't find them in shields easily, so I fletch 4 incher's where there are lots of options.
I have finally got my shafts and points so well tuned to my bow that even two four inchers will do the trick.
One thing is that I have backed off an aggressive helical to a pretty tame offset because they were noisy and I started noticing that the straighter fletches were a little deeper into the block than the others. But neither issue is enough to justify ripping the feathers off and redoing them. I don't have a chrony.