Most golfers would like to be able to hit a golf ball further, but this does not always mean hitting the golf ball harder. It often requires hitting the golf ball smarter.
From a stable address position; the backswing shoulder turn creates a powerful coiled up position. However, as a golfer starts in the downswing, they should be careful to not release all of this valuable coiled up power too early. The important phase is through the impact area where the club head should be accelerated to maximum velocity as it makes contact with a golf ball.
If a golfer is guilty of spinning their shoulders at the start of the downswing and opening their body up too early, the golf club could be accelerated prematurely from the top of that swing. This could also throw the golf club out of line which ultimately could create a lack of accuracy on the golf shots.
Instead, the shoulders should be maintained in a slightly closed position for as much of the downswing as possible, at least until the hands have dropped below the hip level. Then as the club attacks the golf ball at the last moment, the shoulders can release their valuable stored up coiled energy to propel the golf club to maximum velocity through the impact area. They should create longer straighter and more consistent golf shots. In the finish position, the shoulders will be fully turned and opened and facing to the target or even left of the target depending on a golfer's level of flexibility.
If you want to hit the ball further, avoid hitting it harder from the top of your swing and hit it smarter by keeping your shoulders closed for longer.