I'll be the naysayer.
My mustang I had at the time got away from me (I was leading him and he bolted) and we were in the arena. He didn't want to be caught so I let him calm down before I tried again. He was dragging the lead rope, but before I even tried to work with him again something spooked him and he took off at a gallop around the arena. When he reached up with the longer stride of the gallop, the rope wrapped around his back leg and the momentum of the step snapped his head down and caused him to nose dive straight into the ground. Thankfully he didn't get hurt beyond a scrapped nose but it was horrible to watch and it had the potential to be worse.
I would never leave a lead rope on a loose horse on purpose. There are other ways to teach these lessons without the risk.
Cat, this is why I was saying I had mixed feelings on the whole thing....there are just things that can go wrong....but at the same time, I feel as if, if I work with him on it, if something does happen, he wont freak out as bad. I don't necessarily say Im going to turn him out the moment I get to the barn, Im going to make sure he gives to the pressure, and use what someone else had said, about stepping on it a little bit, and having him give to that pressure.
I appreciate your opinion though! That sure sounds like a scary thing!!! Would have hated to see something like that. Glad it wasnt as bad as it could have been!!!