That depends on how accurately the player uses fractional references. In other words, a beginner using fractional aiming could be off with their aim line estimation by 1/8 of a ball or even 1/4 of a ball while standing. If they recognize how far off they are once they're down on the shot, then there's going to be some movement/adjustment needed.
Using a little math it's easy to determine how much adjustment (in tip offset measurement) will be needed. Let's say the player is off by 1/4 of a ball, which is quite a bit! Lol. Anyway, the ob is 6ft away from the cb and the player incorrectly lines up for a 3/4 ball hit. When he bends into the shot he sees it looks closer to a 1/2 ball it.
The alignment difference for this shot (difference between a 3/4 aim and a 1/2 ball aim with the ob 6ft away) is only 0.45°. In other words, his aim line through ccb is 0.45° too thick. This equates to a 2mm offset on his alignment. That 2mm would be a 1/6 tip pivot if he wanted to adjust by using a pivot type method. That's not much movement or adjustment when compared to using a 1/2 tip pivot.
If the ob were only 2ft away, then the required adjustment from a 3/4 ball aim line and a 1/2 ball line would be about 1.3°, which equates to about a 1/2 tip pivot if that's how the player makes his adjustment.
Math....
Angle difference in 3/4 ball aim and 1/2 ball aim for ob 6ft away:
2× atan(0.28125" ÷ 72") = 0.45°
Required pivot for a 0.45° adjustment in shot angle using a 10" (254mm) bridge:
tan(0.45°) x 254mm = 2mm
A 2mm offset pivot using a 12.5mm shaft is about a 1/6 tip pivot. (2÷12.5 ~ 1/6)
Angle difference in 3/4 ball aim and 1/2 ball aim for ob 2ft away:
2× atan(0.28125" ÷ 24") = 1.34°
Required pivot for a 1.34° adjustment in shot angle using a 10" (254mm) bridge:
tan(1.34°) x 254mm = 5.9mm
A 5.9mm offset pivot using a 12.5mm shaft is about a 1/2 tip pivot. (5.9÷12.5 ~ 1/2)