The approximate length of time that it takes to complete the task. APM uses this information when a task is placed on a schedule.
You can enter an estimated duration, or APM can calculate the duration based on the trade, tool, or time-based service requirements. To enter a duration, clear the Calculate option.

The system calculates the task’s estimated duration. APM sets the task’s estimated duration to the trade, tool, or service requirement with the longest total duration (Lag time plus the Required for time).
One mechanic: 4 hours, 0 lag (4 hours total)
One electrician: 2 hours, 3 hour lag (5 hours total)
One mechanic: 2 hours, 5 hour lag (7 hours total)
Alternatively, clear the Calculate option to enter the estimated duration.