In my opinion people will get better grouping when aligning the blades with the fletching but not for the reason they think. If the arrow heads are not all aligned the same on each arrow they will each catch air a little different when the arrow is launched. The better the bow is tuned the less the arrow will deflect off course before stabilizing but there will always be some deflection. The trick is to get every arrow to have the same relationship between blades, fletching and arrow rest even if the blades and fletching aren't inline with each other. Just my $.02.