What do you think of this training method?

So we're completely re-starting my mare from the ground up.. To work on her head set and no tossing her head, my trainer put her in a simple snaffle, took long cotton split reins, crossed them and put them through/under her legs, then brought them up and tied them on her back to lunge her. It was relatively loose, so when she hit the end, she would lower her head and leave slack in the reins.. It seemed to work, what does everyone think? Is there a more effective way, do you think it's a bad technique?...