Lead Hand Only
Why this drill
The lead hand is the stroke's steering wheel; the trail hand is where the yips live. Putting one-handed with the lead hand alone strips the stroke to its rocking core and teaches the shoulders to move the ball — because the hand by itself can't.
Setup
Ten balls at four feet from a flat hole. Trail hand behind your back or in your pocket — actually away, not hovering.
The drill
Ten putts, lead hand only. The first few wobble; let the shoulders take over and the wobble disappears — that transfer is the entire drill. Count makes. Then five putts with both hands on, trail hand at half its usual pressure, keeping the one-handed feeling. Most players hole more four-footers immediately, because the trail hand finally stopped helping.
One thought to take with you
Rock the shoulders; the hands are passengers.