For all completed requests, we use the Date/Time the Job Request was marked as Completed minus the Due Date/Time

Example:

Job Request A

Completed on 15/5 at 10:00am
Due on 15/5 at 9:00am

Efficiency is +1hr

Job Request B

Completed on 15/5 at 10:00am
Due on 14/5 at 9:00am

Efficiency is +25hr