I personally like to use a 4 blade more than a two or three blade. The reason is that as the skin and muscle stretches a 4 blade actually leaves a round/square hole instead of a slice or triangle.
well if you have your bow firing on all cylinders so to speak you can take the blades and line them with the vanes and that makes it fly nicer, which obviously makes for less drag, 4 blades theres' only 1 that can be lined up. I've always done it and I don't use the ones that don't line up. I don't know seems logical to me everything's in line less drag and more like a field tip.
That is all nothing but old wives tails passed down from generation to generation. When you get the math figured out to actually get this to work in a 100% controlled laboratory environment let me know and I (mother nature) will change the wind direction so you can throw all of your work right out the window.