I started out with the old Mercury "speed" nocks that had NO grip on the string at all. So for me, I like a loose nock and certainly nothing more than a light tap on the string that will release the arrow.
Yes, for those that started out with snap on type nocks, a loose nock is a recipe for a dry fire but I respectfully submit that that is a case of not paying attention, or having so much "finger protection" that you have no feel for the arrow on the string.
Obviously, 3 under requires a snap on nock.
If it takes noticeable effort to place or remove the nock on the string, that is too tight, IMO.
Arne