I want my arrow to extend one inch beyond the back of the bow plus the length of the head, regardless of whether I'm shooting high or low weight arrows or high or normal foc. Pretty easy to do with wood. I don't like my arrows to be any longer than necessary for two main reasons. First, in a bow quiver, the arrow nocks often stick in the dirt and fill with dirt when one leans the bow against a tree, for example. More importantly, longer arrows reduce maneuverability. It's amazing how much an extra inch or two of arrow length will result in not being able to maneuver the bow with arrow nocked in tight quarters, say in a tree or blind, including ground brush blinds. On the practice range, of course, length makes little difference.