everyone will have their own idea- but this is what i do- i shoot 3 under- and i like two nocks- tied on nocks- look at S2 bowstrings- he has some great tutorials for that. i tie the nocks just a tad further apart than the arrow nock- so when the bow is drawn back and the string is drawn to an apex- that the tied on nocks arent pinching the arrow nock, and jambing themselves into the nock- but too much play may result in imperfect flight- i would imagine.
with 2 nocks the arrow does not slide around on the string, say while an arrow is nocked while i am sitting, and my draw hand is not on the string.
anyway just my thoughts.