As has been stated, it depends on your set-up. The generally accepted guideline of ideal nock fit is a light tap on the string will cause a dangling arrow to fall off. Mine aren't that loose but, too-tight will adversely affect accuracy and noise also. I don't know if the inventor of this rule ever heard of snap-on nocks, but they will generally slide along the string easily and can't be easily dislodged by tapping the string. If they slide on the string, I use two with about a 1/8th" gap below the bottom of the nock to allow for angle at full draw.