Having blades aligned with fletching is bunk like the guys said.

BUT, I have found (for me) that keeping the blade's position CONSISTENT from shaft to shaft can help. For example, like if you're using a three-blade, keep one blade straight up (or whatever position you choose) when the arrow is nocked on the string. If the arrow is flexing a bit on launch, having consistent position of the blades can help with repeatable arrow flight, and certainly can't hurt.