About twenty years ago, I saw something like that in a gym. They had a kid, maybe 14 years old, 112-115 pounds, that was pretty good. He'd won some 50 amateur fights and they were preparing him for a tournament. Every Thursday he'd be in the ring for two hours and he'd spar everybody, all the kids in the gym, up to a 25 year old 220 pound southpaw. Personally, I thought they were trying to kill him.
A dozen years later I saw, in another gym, the same sort of thing. This time, the guy that would spar everybody had been the national #1 amateur in his weight class and was preparing to turn pro. He'd spar with everybody, every night, and fight 'for real' 4 round sparring sessions on Saturdays. With him, it was just work because he knew how to fight (currently 13-2 as a pro) and rarely if ever took a clean shot.