Does an extended follow-through add power, draw action, or accuracy to a shot?
This is a question of cause and effect. The follow-through strictly has no influence on the cue ball because the cue ball is gone before the follow through takes place. What the grip and stroke does during cue tip contact is also unimportant because the tip is in contact with the cue ball for only a very short amount of time (approximately 0.001 seconds). However, the follow-through is usually a good indicator of the quality and nature of the stroke into the ball (before tip-ball contact), which does matter quite a bit. For example, if the follow-through is very short, it could indicate a decelerating or over-constrained stroke into the ball, which can adversely affect speed control. Also, if the follow-through involves tip lift (e.g., due to grip tightening and/or elbow drop), steer (e.g., due to a flying “chicken-wing” elbow), or exaggerated forward extension (e.g., due to excessive shoulder and elbow motion), these motions might be starting before tip contact, during the stroke into the ball, and this could definitely affect cue-tip-contact-point and aiming accuracy. To summarize, a good and appropriate follow through is not the “cause” of a good hit, but it is often a strong indicator of a good stroke into the ball (before tip-ball contact) … which does affect the hit.
All the cue ball “cares” about is tip contact point, cue speed, and cue angle and elevation at the moment of impact. Follow-through is just a symptom of your stroke and has no direct affect on the action of the shot. Now, when you follow through, maybe you are doing something different with your stroke to get a different cue speed or a different tip contact point, or maybe your stroke is straighter. To detect this, you can videotape your stroke changes and look at the chalk mark on the CB. It helps to use a ball with markings (e.g., a striped ball or a Jim Rempe ball) when checking the chalk mark. If two shots have the same cue speed and tip contact point, but have different amounts of follow through, the action of the shots should still be the same. If you are getting different action, you are not hitting the CB with the same speed, tip-contact point, or aiming line. With an elbow-drop (long follow-through) stroke, there might be a tendency for the player to drop the elbow slightly before CB contact. If this happens, the tip will hit the CB slightly higher than the player thinks. Likewise, with a shorter follow-through, a player might have a tendency to tighten the grip slightly, which would cause the cue tip to lower some. Also, different cue speeds will result from variations in the stroke. For more information, see stroke “type” and “quality.”
Concerning the break shot, the only thing that significantly affects the power for a given break cue and tip contact point (and cue angle) is cue speed at impact. However, if a powerful stroke does not exhibit a long follow-through, it is either not very powerful, or effort is being made to limit the follow-through. If one tries to constrain the follow-through, one will probably not achieve maximum speed at impact.
Follow-through can also be important in achieving good action on draw shots (although, not always for the reasons people think). For more info, see “Draw Shot Primer – Part V: how to achieve good draw action” (BD, May, 2006). In particular, see item “b” under “other advice” and item “5” under “suggested best practices.” I think these points apply equally well to both a power break and a power draw.
For more information on topics related to follow-through, see: