Ok so if I do this everybody says I will be underspined...So when I look at the "pros" set-ups they have listed on their sites then they also shoot underspined...Why??

For instance one pro set-up I looked at shoots the Easton Flatline 400 with a .400 spine..I'm guessing this persons draw weight at 70# but their draw length is 29.5" and they shoot the Reezan..By the Easton Shaft selector that isn't even a recommended shaft and by what you all are telling me that would be under spined..so why shoot it then?? specially if your a TV pro??