I have mentioned many times over the years, to keep “constant” grip pressure during the entire golf swing. This concept really lets the body take control for a more repeatable swing. I’ve discovered that a certain number of golfers, will keep their grip pressure constant, but through impact, they allow their “arms” to take over trying to add speed/distance. What happens when the arms take over is, the body stops to support and help “sling” or speed up the arms. This works against what we try to do using the Large Muscles.
If the arms take over, they usually pass the body’s rotation, pulling the shots (if the face is square), or cutting the shot if the face is a bit open.
The answer, is to learn to rotate using the body’s rotation without the arms helping or taking over through impact. If you start with a short, shoulders-only backswing, then a medium paced, complete rotation to the finish… like 40 yd. shot. You can really feel if the arms take over. You want to practice this shot to the point you can rotate without any grip pressure/arm pressure change. Then, just lengthen the backswing a bit as you improve.
There is nothing wrong with having a “firm” constant grip pressure (to maintain a square face), and a squeezing of the elbows towards each other to help keep control.