Sometimes I fall into something quite by accident and I find out that it works really well. Most of the time these accidents don’t work so well, but here’s one that does, in regard to putting.
When I take my stance, my upper arms arm press lightly against my torso. Don’t worry, this isn’t anchoring. That only applies to fixing the forearm(s) against something.
Try this. Sit in a chair, press your upper arms lightly against your torso, put your forearms straight out (parallel to the floor), and join your hands.
Now swing your arms back and forth, sliding them against your torso. See how your hands return to their exact staring spot?
If you putt using this setup and motion, your putter will moving along the right path when it hits the ball, and the putter face will be as square as it was at address.
What more can you ask for?
For short putts, your torso doesn’t have to turn, but for approach putts it’s O.K. if it does, and it should, actually.
Combine this with spot putting and you’ll be way ahead of the game, in my experience.