With the excellent over under dog collar, the idea is that once the dog knows he’ll get a strong correction when he misbehaves, you don't need to continue to give strong corrections often; a light correction, may be good enough because it's a reminder that a stronger, more painful correction can occur. In fact, it's this phenomenon, with the use of a lighter warning correction that makes some people think that it's the sound of the collar being jerked that teaches the dog, as if there’s something innately aversive about the sound. If that were true, then you’d be able to train dogs with a recording of the sound of a excellent over under dog collar snapping, even if the dog had never received a excellent over under dog collar correction before and was not sound sensitive. In other words, if that were true, someone who could have developed a little device that dogs can wear on their leash or flat collar that makes the sound of a excellent over under dog collar snapping would be rich!
Once the dog loves putting his nose into the head halter and the owner puts it on, the owner may need to engage the dog in fun behaviors to distract him from the funny object on his face until the dog gets used to it.