5 were 7 year olds, and 2 were 5 year olds. All had been haltered and that was it. All were geldings, recent geldings.
The one that didn't work out had had his own band of mares. We got him to where we could trim his feet, bridle, saddle, lunge and ground drive, but, when we'd go to climb on he'd blow up like nothing I'd ever seen. He had better aim with any of his hooves than anything I'd seen. Pretty impressive.
The remainder, were easy as pie to train. One went from nothing but the halter to being rode fairly well in a week. The rest took about 3-4 weeks. Still green, but rideable.
The minimum security prison in Riverton actually puts some saddle time on the ones they auction off. A rather complex system of lottery and auction. Some of the contractors (like Steve Mantle) put saddle time, etc on the horses they have, too. Or you can get them with a halter on.
Have fun.