if you start to make Native style bows with shorter draw,, you will see that to get an arrow to fly or the right spine,, leaving them long is a solution,,the tips were sometimes bird points, so not much weight up front, the shaft being longer would help get the right spine,,, I usually cut my arrows to shoot well out of the bow based on how they fly,, the length is secondary,, shorter to make them stiffer and longer to make them weaker,,