Keep in mind that when someone slices the ball, their body is moving faster than their arms and club. A person who hooks the ball too much is doing the opposite. Their hands, arms and club are moving faster than their body. Since most people slice the ball, it is easy to see that it is almost impossible to swing your arms too fast.
The swing plane
The swing plane is the angle at which the club travels throughout the swing. There have been numerous theories about which swing plane is
the proper or best swing plane. After viewing thousands of golf swings, both amateur and professional, our conclusion is that the swing plane has not been properly described to date. Hogan, in error, considered the swing plane to be like a plane of glass resting on your shoulders. Most golf instructors today draw a line up the golf shaft and consider that the plane. If you are able to maintain a swing path that is parallel or directly on the original shaft angle at address, then your chances of returning to your address position at impact increase.
For example, if you were to swing the golf club very steep to the plane, or original shaft angle at address, then you must make a rapid adjustment to reroute the golf club back to the plane or address angle. Not impossible to do but far more difficult.
Here is a good example of keeping the golf club traveling on a proper plane.
Notice that the address plane and the impact plane are not exactly alike. The golf club is in motion and your thrust toward the target will make the golf club attack the ball from an angle slightly higher than the address position. This is why the toe of your club head should be slightly off the ground at address to accommodate the higher plane at impact.
The impact point is simply another location along the swing path. Of course, in mechanical terms, impact is the moment that matters. However, it is not the thing that should matter most in the mind of the golfer. It is more useful to imagine where you are going in the swing rather than where you are at a given moment. This is the reason we would like to limit your focus on impact.
The most important thing to understand is that the golf club head must be as close as possible to 90 degrees from the path of the golf club in order to hit the ball straight. Your left wrist should feel slightly bulged at impact. The left leg also straightens at impact.
Immediately after the impact position, the forearms rotate, allowing the golf club to remain square to the follow-through path and allowing the left arm to bend. One might need to feel as though this is happening before the impact area, in order to accomplish the club face passing the hand position through impact.