I think that breezing a horse can be very beneficial to build up stamina and confidence. I really like to do this with my younger horses that are still learning how to run. I personally like running on a track or in a field that I have checked for gopher holes. I only breeze my horses one day a week. I do not find it very helpful just sprinting my horses in the arena. I think it confuses them and is more counter-productive then anything in my experience.