If you use a loop that goes over and under the arrow nock, you should make it long enough to prevent the release from touching the nock. Also, if you use a hand held release that you rotate at anchor then the loop should be long enough to prevent it from torquing. Probably 3/4 ". If you use a loop completely under the arrow nock then you can make it as short as you want. I personally use the completely under loop as I have just found it to be more accurate.