In general it would be stupid to expect things to be different. What kind of creature gets better because of being locked up for years with a bunch of other worse-than-average creatures of it's kind?
Incarceration, if done properly, might make people less likely to reoffend simply because they get older and their health gets poorer, thus having less energy and becoming less of a nuisance. But that's not done because of insufficient prison capacity. They nearly all get out while still young enough to remain a massive problem.
