The slope is a riddle, really. If you view it from the enemy’s point of view, a 30‑degree angle keeps the approach slow enough that you can react, but from your own, a 60‑degree angle maximizes your field of fire—so it’s both angles at once, and you have to decide which one you trust. In practice, I’d lean toward a moderate 45‑degree cut, because that gives you a little of each, but the truth is the angle is only useful if the defenders keep their heads down and their eyes on the ridge.