But that in a nutshell is what clicker training is about. If you know how to get the horses' trust, you do not need no gimmicks. I don't know why we can't get back to basics. I have to retrain too many that have been given treats. Agreed, don't do it if you don't know how to control it.
Horses are a Very quick study.
Maybe even just once. It was not the treats it was the trainer. They have great timing and feel, they care for the horse, they have a sense of awareness, they understand what the horse needs in order to make the step to the next level of learning. The existence of treats or not is irrelevant. Once learned they discover they apply to everything.