In a case where there might be a single production machine producing a total number of hours of production capacity by running multiple shifts, multiple jobs would be scheduled to run consecutively.
In a case where there might be several similar production machines producing a total number of hours of production capacity, multiple jobs could be scheduled to run concurrently.
An example might be 1 Press running three 8 hour shifts for a total of 24 hours of daily capacity. In this case 1 job could be run at a time. Multiple jobs would need to run consecutively. The opposite would be the case for 3 of the same presses each running 1 - 8 hour shift during the same time period where three jobs could be running concurrently.