I'v heard all kinds of theories from it just dont matter to you need to line the blades up with the fletching. (kinda hard with 2 or 4 blade heads)
My own experience leeds me to believe that the orientation of the blades doesnt matter so long as they are all the same. I put a blade on top & thats directly oposite my fletching but it males it instantly obvious if a head rotates a bit. I think it has to do with the shaft flexing upon release & the heads effecting how the shaft reacts when straightning out. I may be totally wrong but if I am I killed 7 deer, every one I shot at, last year the wrong way. I cant see whats wrong with that.