[Macbow]

Use whatever works best for you. If 5" shields give you good arrow flight then great. Personally I prefer 4" parabolics with as much helical as possible. Bigger higher profile feathers offer more stabilisation (at the expense of a few fps) and can go someway to offset a less than perfect release but if you tune your bow/arrows properly smaller feathers will do the job just as well but with less drag. Anything that gives you a slightly flatter trajectory is a good thing IMO especially when it comes to the 70 & 80 yarders. Try bareshaft tuning so you know you are getting good flight out to 30 yards, fletch four with 5", four with smaller feathers and see if there is any difference at every range.