This certainly gels with something my mate, the ex trainee pro, from my club told me a couple of weeks ago when we were talking about my putting.
He asked me to hit a couple of putts dominant (right for me) hand only and I found line was fine, though pace was erratic. Adding in the non dominant hand after a few putts, and focusing on hands rather than shoulders, saw me lag putting much better than ever I had.
Since then, those 2 3 putts last saturday aside, which I put down to the fact that I was thinking about winning and not holing the putts, I have putted quite well.
I take it one step further myself in that I now think of my days on the tennis court and images of me rolling tennis balls straight along the ground on target lines when returning balls to the other end when I was receiving serve.
One other thought, I'm now of the opinion that by focusing on the shoulders, you in some way hope to take the hands out of your mind when putting, hopefully then there will be no wrist break. For me, now focusing on the hands only, I find I'm more aware of them and I don't break my wrists at all and I'm much more able to control speed.
Cheers
PS... Come to think of it, doesn't one of our fellow forum members (Bill from memory, and all apologoes if I recall incorrectly) here putt "sidesaddle" to the target line, with a broomstick putter...??