What is the key difference between lag and lead time in scheduling?

The key difference between lag and lead time in scheduling is that lag time delays a task, while lead time accelerates it.

In project management, lag time refers to the intentional delay between a predecessor and a successor task. It is used when one task cannot start until another task has progressed or completed to a certain degree. For example, if a construction task can only commence after a previous task has been partially completed, a lag time might be added to allow for this necessary delay.

In contrast, lead time allows a successor task to begin before a predecessor task has fully completed. This is beneficial for overlapping activities, enabling tasks to be performed concurrently or to start sooner than they otherwise would have, therefore accelerating the overall schedule.

Understanding these concepts is crucial for effective scheduling, as they can significantly influence the timeline and coordination of project activities.