Most people don't really understand the system. Here in New York if a person is sentenced to say 1 to 3 years what that means is after the 1 year is up that person becomes eligible for parole. If the Parole Board releases him, HE REMAINS UNDER THE SUPERVISION OF PAROLE until he has completed his sentence (which is based upon the 3 years although that is then usually reduced by application of "Good Behavior"). Remaining under the supervision of Parole for the remainder of the sentence actually is a significant societal benefit. PAROLEES may be returned to prison for conduct which does not constitute a crime and with less evidence than a criminal conviction would require. If an indeterminate sentence was not used, most likely the guy who would have been sentenced to 1-3 would have been sentenced to 1 yr not 3 yrs. Now the sentence is actually being increased to 1 yr followed by additional time under supervision of parole or in prison. The specifics may vary from State to State but that gives you a general idea.

There are some programs which work differently and result in early parole, such as boot camp and certain drug treatment programs, but even under these programs the person remains under the supervision of PAROLE based upon the the maximum term not the minimum.