It depends upon what your goals are with your bow. Use just enough to make the bow tension safe for its intended draw length. If its underweight your intended goal, add more.
I tend to think many people use more sinew than they actually need to, slapping on two thick ugly layers, then another course down the crown.
Re amounts for one bow, I couldn't say because I get mine from in bulk from other hunters that give me whatever they can and I process all of it into finely combed stands, and stick it all into snaplock bags, take out what I need as I go. It might be years before I get around to using it after processing the tendons, so I can't remember how many I originally processed. The stuff last almost indefinitely unless the bugs or some other pest gets to it.
