I do remember that the 40 strokes less one thing was only for Roman citizens - like Paul was. But those who were NOT citizens, like Jesus, would not have been subjected to such restrictions. That is my understanding of the matter, but I could be wrong.
You'd be surprised at what people can endure - I've read some amazing accounts of survival despite serious beatings. I once attended a historical program about the convicts in Sydney Australia, where flogging was a common enough punishment. The descriptions on certain aspects of the beatings defied descriptions.
Besides that, working as a Nurse's Aide, I know that people hardly ever die easily. Life is tenacious. I once helped clean a man whose bedsore in his back had rotted away the flesh until, literally, his ribs were exposed and certain organs, (I only recognized the kidneys when reading an anatomy book later), were pulsing beneath a necrotic membrane. And he was not only alive, he was cranky and kicking and funny. (I vow to never go to a nursing home or send my family to one - unless I live in the area and show up every day to help clean and turn them. It is disgraceful and ridiculous; some of the conditions were deplorable.)
So, if a cripple can survive rotting in half, I guess an ostensibly perfect, or at least healthy young 30 something, could survive a severe beating on his back.
CZAR