The time that prisoners get to spend outside depends on what prison the inmate is in and what the prisoners custody level is.
For prisoners who're in minimum custody they can sometimes depending on the prison spend up to 8 to 9 hours per day outside in the rec yard until it's time for lock down at night.
If a prisoner is in maximum custody or in a prison such as ADX Florence then they can only spend around an hour outside in a tiny cage and they must be escorted by a couple guards in cuffs and leg chains to and from the Rec Cage.
In ADX Florence Colorado Prison the prisoners spend 23 hours per day in a tiny cell with only a tiny window to see out into the concrete wall and sky.
Once per day or once every few days the prisoner at ADX Florence is allowed out for one hour in the cage to get some air and then it's back into the Cell for 23 more hours.