The ONLY time I consider draw reins to be appropriate is on a horse who dangerously throws his head up and bolts and otherwise cannot be brought back to control. That's it that's all.
Learn to ride to get the head down and in the right place, your horse will thank you and come the next horse - you will know how to do it withough relying on gadgets!!
I owned a horse who's neck and spine were ruined by use of gadgets (a dugoug specifically and used mostly, although draw reins, a german martingale and other things were also periodically used) to the point where she is so neuro and lame that she cannot be ridden and was retired before the age of 10.