A horse can only be straight when the mind and the body are travelling in the same direction. If the mind is going straight, but the body isn’t, then the problem is either physical weakness or a rider issue. But if the mind is not straight, the body can never be straight.
Conflict
When I Am Made Emperor of the Universe
Watching Horse Training Videos
If the horse has a soft-focus, a quiet mind, can follow the human's feel with no trouble, and is okay to have its thoughts interrupted with a new idea, then I want to know more about the trainer, the philosophy, and methods. If those things are working well for a horse, the method can’t be wrong for that horse at that time.