Huh. Trigger and I do this almost as much as going forward... so many circles. Lots of circles. It keeps his feet moving while giving him a chance to 'come back to me' emotionally.
If you just haul back on one rein at a full gallop though, you'll lay the horse down like in an old west movie fall down, and you really, really don't want that.
I'd LOVE to know her take on the pulley rein, as asked by Dreamcatcher, though.
"We are here to laugh at the odds and live our lives so well that death will tremble to take us."