Examining Capacity and Priority:

Set the Schedule by Simultaneously Examining Capacity and Priority, not sequentially. Lead Times are the Result of a Schedule and may not be Predetermined

In a tradition system (such like, MRP), the lead time is fixed and predetermined. Though, OPT advocates that scheduling must identify that lead time is not essentially a fixed quantity. It can vary as a function of schedule. Thus, the schedule must be set by examining the capacity and priority simultaneously.