Most prisons have rules allowing you to stay for 1 hour at a time when visiting the prisoner.
So you have 1 hour to visit with the prisoner before the prisoner has to return to their cell and you have to leave after that hour.
An hour when visiting a prisoner goes by so fast especially since you can't see them that often.
Sometimes if you live further away from the prison where the inmate is housed at you can sometimes schedule another hour or 2 for the prison visit but it's not guaranteed.