Lil' one of the things I've noticed with too loose a nock is that I can't shoot with my most effective grip. I use a Mediterranean grip (split finger). When doing so, I try to avoid even touching the nock with my index finger and barely put any pressure on the nock with my middle finger. This gives me the most consistent release. If my nocks are too loose, I have difficulty keeping them on the string using this type grip (a sure sign of time to replace or tighten the nock.)

Jack