Check out these golf drills focused on single balance, tension, and swing drills.
In-season training off the course will be significantly different than off-season training for professional golfers. This video demonstrates some exercises from an in-season program for a professional golfer. The focus now is on maintaining power, balance, dissociation, and some overall maintenance.
Using a sports cord around the waist or torso wrapping with a band is an excellent way to drive acceleration and deceleration drills for rotational athletes. Depending on how you position the person in relation to the anchor, you can focus on acceleration drills to improve power OR practice deceleration drills focused on balance. For golfers, I highly recommend BOTH especially in season. It is essential to include sport specific movements at high intensities during in-season training.