I am guessing a bit but I am understanding 'gain time' to be accrued time. I think 'score out to' was 'sentenced to'. If I read it right they are saying (most

I am guessing a bit but I am understanding 'gain time' to be accrued time. I think 'score out to' was 'sentenced to'. If I read it right they are saying (mostly) the time spent in jail does not accrue days off a sentence like the time spent in the prison would.