About 7 or 8 years ago, I got into 4 fletch ...... 4" shields, 90 degrees. I loved the way they flew and I was happy and shot that set up for several years. All fletch mentioned here are shield cut. Forget exactly why, maybe cuz I got a new bow I'm thinking, I ended up shooting some older 3 fletch 5" that I had in my surplus. They flew very nice. Built some 4 fletch on the same shafting model as the 3 five inch fletched ......and they did fly very nice also ...... BUT ........ I noticed there was a very tangible sound difference between the 2! The 3 fives being much quieter! I had never compared the 2 side by side, and was so used to the 4 fletch at that point.
Flight was very similar if not exactly the same, I could see the 4 fours better in flight no mistake, but the 3 fives were like a soft breath compared to ever so slight hissing quill noise the 4 fletchers made in flight. Maybe it was the culmination of all things tuning wise with my tackle .......maybe my ears are sensitive.......maybe I'm nuts. However it may be, I'm all about the 3 5inchers now again and my money is on not going back to 4 fletch. Was the sound difference enough to make a difference if shooting at game? Well not exactly sure but figured if it were a noticeable difference to me with human senses, it might just be the same or more significant for the critter senses and maybe I'm better off without that variable. Just my experiences and observations on the matter for me.