I think it depends on the student. For some, I would never dream of pushing. Upon crossing their limit, some would leave class upset and never return. Some will feel a victory and go home 10 feet tall, itching for the next lesson to come around.
I remember being about 10 or 11 and receiving Tomenage from my Judo teacher. He didn't tell me what he was going to do and the next thing I saw the floor and ceiling fly by and then I landed on the tatami. I went home feeling great.