$bowhunter$. On the first three to four feathers that come of the wing, they are the main primaries and for the most part will give you two 4" or one good 5". What you have to look at is the back end of the last cut of the second 4" is going to be very narrow and not much to glue down. Not only that, but when you mix and match the cuts of feathers, that is exactly what you get, mix matched fletching. On secondaries, I only make one chop from them.
What most people like to think is that if the feather they send me is 14" long, they should get two fives and a four inch cut out of it. NOT!!!. If you look down a primary feather, on the end that goes into the wing, you will see a bulge, bulb, whatever you want to call it about 2 sometimes 3 inches from the end, and the feathers actually start turning into the center of the quill. You can NOT grind this, it is cut off. And if you split one, you will see that the back end when ground will go to almost nothing to glue down with.
My best recommendation to you is think 1 really great cut from any feather, and then take what you get as left overs. There is no way to say how many give you what. If a quill has a shot hole in it, NO GOOD. If the feathers are shot off the quill, NO GOOD. There is no guarantee of what you get back...NONE.
Hope this explains it better.