Several factors come into play that will dictate best size and angle of set of feathers or vanes for a shaft being launched off a particular bow. A straight fletch will impart some spin to a shaft. The question is; is it enough spin for your setup.

Most high-energy bows launching lightweight shafts often need more and quicker-acting stabilization (feathers/vanes). Hence, 5" feather/ vanes with a helical set are often required. Feathers stabilize quicker so the same shaft might get away with a slight offset. Some setups might fly quite well with a straight fletch.

My 43" ATA "Dual Wheelie" Martin shoots heavy shafts with straight 5" fletch (feathers) with very good flight and accuracy. My "Sonic Wheel" compounds (more energy) require a 1-degree offset for best flight and accuracy.

The only way to know what setup is best for you, is to shoot your shafts using different feather/vane setup until you find the right combination.