These things have a balance, though. If you're planning on letting people out of prison one day (i.e. if they don't have a life sentence)...
And it's punitive to the point that familial relations break and people lose what little support network they have and ability to live outside of prison...
You can expect they're going to show back right up where they started. In which case, by facilitating repeated recidivism, you've neutered deterrence, incapacitation and left them unable to make meaningful restitution.
Even for life sentences I believe it makes sense to have prisoners work and earn some small privileges inside.
For one its possible to encourage good behaviour by threatening to take it away but also because a sense of purpose and achievement is important for a healthy mental state. That's true for incarcerated people as well and a stable population reduces enforcement costs and churn among the guard personal.
These things have a balance, though. If you're planning on letting people out of prison one day (i.e. if they don't have a life sentence)...
And it's punitive to the point that familial relations break and people lose what little support network they have and ability to live outside of prison...
You can expect they're going to show back right up where they started. In which case, by facilitating repeated recidivism, you've neutered deterrence, incapacitation and left them unable to make meaningful restitution.