I'm guessing up til now, the days of time off earned was done in real time. Basically all you need is the day they entered, divide by 6 and truncate and there's your days. If there are infractions that cost days, you could still probably do it in a single SQL query.

This new system will have to know what kind of crime they committed, which might mean integrating with some byzantine government software from the 90s that looks like it's from the 70s. Previously they only really needed the prison system's records, which may or may not include their past crimes.

I'm guessing they're worried the integration won't be as easy as proposed. I wouldn't be surprised if it takes a month just to get the dev access to everything. I might even be surprised if it was that short.