I shoot split, so I do not use two nock sets. I have a good friend, who is a very good shooter, like top ten in the state of Tx. This guy does not know squat about tuning. He asked me for some help on a recurve he had. We messed with it and just could not get good arrow flight, no matter what adjustments we made. As a kind of last resort, I noticed he only had one nock set, and told him, "Let's try a second nock set". The next shot was perfect and so were subsequent shots. I am a true believer now, that if you shoot 3-under, you should always have 2 nock sets on your string.
Bisch