My experience is you can get a horse as broke as a puppy dog and the owner can take it home and still get hurt and mess things up.
I know a horse that showed very well, was nicely broke, had done well in western pleasure, was known to be if anything a little too lazy, and he 5 years old. He was turned out twice a week on Mon and Wed. He was ridden on average 5 days a week for 1-2 hours(on average). This was mostly warming up at the w/j/l in the arena then trail riding. Once a week (during lessons with a pro) they practiced their WP for shows.
They decided to sell him and move up to a better bred horse.
He was sold to a girl who, after purchasing him, kept him in a stall 24/7 for 7 weeks before finding the time to work/ride him. (the horse was boarded at the same farm). She tacked him up and took him to the arena then got on him and walked him around. They got one lap down before he suddently galloped off; she fell and was hurt (broken arm and badly bruised hip). The gelding was given back to the owner.