Is this a nice idea?

Unless the book is
" how to be a terrorist"

theyd come out so intelligent to not kill someone

"Hey Frank, what did you think about the unsubtle metaphors in "Animal Farm"?"
"I thought it was a sequel to "Charlotte's Web"!"

As a brazilian i can say that this does not happen, most prisons are overpopulated with over 4 times the maximun capacity, and they let people out before the sentence is over a lot because there is no space for the new prisoner that just arrived