My loop lenghth is determined by what release I am using, the bows DL and how much loop length I need to reach my anchor point. GI get the bow's DL set up to where I want it, and then tie a loop to the lenght I need. It takes a little trial and error when messing with a new bow or release. My loops are probably longer than most, but that's because of the shape of my face, and the distance from string apex (which I want under my eye to maintain alignment and minimize facial contact) to anchor point, depending on rlease being used. Shorter release head, longer loop on the same bow, than a release with a longer head.