You can model operators that can run more than one job at a time using the ‘sharing’ mechanism of the planning system, e.g.

Here the machine takes 5 minutes per thing but the operator is only needed for 1 minute of that, so he has 4 minutes available to do other things. If the operator resource is marked as sharable, the planning system will run up to 5 of these jobs at once using the same operator.

Internally the planning system tracks elapsed time and allocated time within that. If the allocated time is less than the elapsed time there is spare that can be allocated to other jobs. The planning system keeps allocating time until the whole elapsed time has been used up. The elapsed time is set by the resource that requires the most time (the Machine in the example above).