This is all about people with a passive cast (Link) who I have told to shorten their swings, but everyone can learn something from this.
Basically every person who has a passive cast is a result of a swing that is too long. I have told them the swing needs to be shorter, and nearly every one of them has given me the same response. The returns have been almost unanimous. “I trust what you are saying but when my swing is shorter, I feel powerless.” Some have added it ruins their rhythm.
If you cast, try to shorten your swing and it feels powerless and/or messes with you rhythm…there is a 100% chance your takeaway is controlled too much by the arms and hands. Once you put control in the shoulder turn and that shoulder turn is near 90* to the spine, you should be able to take any club, including driver, any length of backswing and not feel any loss of power or rhythm problems.
The reason this happens is if your arms are controlling the swing and you take it back shorter, the feel is they have no space or leverage to create any speed. Often an arm swing in a shorter position gets the club behind you and you can’t accelerate from that position or you won’t hit the ball properly, so you have to just drop your arms on the ball. That is where the powerless feel comes from. You can create speed and leverage from any point in the golf swing if your shoulder turn is in control and your arms and hands are in front of your chest.
This is all a lot of mumbo jumbo explanation for those that need to know. The simple solution is to make a shoulder turn that is 90* to your spine. Easier said than done if you are used to swinging your arms, but that is you one swing thought.