So I saw one of the teens at the barn put a neck stretcher on her horse, turn him out in the arena and chase him around with a lunge whip. I asked her if that was really a safe idea. Her response? "I'm supposed to do this." Apparently the woman she's taking lessons from (3* event rider) thinks this will help her horse build a topline and stop throwing his head about. She also said she's supposed to do it loose, not on a lunge line. Am I nuts for thinking this is a bad idea?
Depends on the horse, and what you're describing as "chasing". If the horse is a steady eddie type, and her chasing it around gets it into a nice forward trot or nice canter so he works into the neck stretcher, I think it's fine. No worse than lunging in it, and is actually easier on the joints.
If the horse is a hot type and her chasing it around ends up in a bolting gallop, then I think it's not a good idea, however, if she IS gonna gallop it around it's better to do it in a large arena than on a lunge line.