Old teaching taught forearm rotation. Modern teaching allows the wrists to release in the way they do for every other sport.
Nicklaus takes 3 hours to hit 30 balls.The greats practice by hitting one shot at a time, and learning from every shot they hit.
The arms move the club out, as the body rotates. In this way, the full swing is a blend of arms and body.
How to start training your hands.