Introducing Lead & Lag in Task Dependencies

Oh dear!  This is another example of someone posting an article without a fundamental understanding of concepts. Lets be clear - Lead and Lag times are NOT Buffers. Buffers are an entirely different thing. Lead and Lags are part of dependencies and reflect the nature of the relationship between two dates associated with different tasks (not always in the same project plan either).  This article simply confuses the less experienced allowing them to use incorrect terminology in project management. 

In brief lets try and clarify the terms for the benefit of the less experienced 

• Lead Time: Allows overlap and schedules a task to start before its predecessor finishes, effectively pulling tasks closer together to shorten the project duration.
• Lag Time: Introduces a delay between tasks, ensuring that there is a necessary gap for tasks that cannot immediately follow one another, for example waiting for paint to dry or for concrete to set (which by the way would be elapsed duration lags, since these are real time lags and not dependent on calendars). 
• Buffers: Adds extra time to tasks or project phases as a safeguard against uncertainty and risk, ensuring that the project has flexibility to deal with unexpected events without derailing the overall timeline. Often buffers are elastic in nature since the buffer time may be consumed and reduced depending upon the status of the tasks and then project. Whilst lead and lag times are typically static periods (although do not have to be - that's dependent upon the capabilities of the software), buffers typically reduce in available time during the lifecycle of the project to the point where ultimately the buffer time can reach zero (although not desirable of course, and typically adjusted interactively by a PM during the project lifecycle). Critical Chain Management uses buffers to good effect in manufacturing concpets. 

In the desktop version of Microsoft Project buffers have NEVER been a feature or capability and required a third party product (typically) to model Critical Chain Management in Microsoft Project.  In fact in Microsoft Project today (Planner) they still are not a feature and this article is extremely misleading. 

And of course, lead, lag and buffers are not to be confusd with constraints which are themseleves a different concept, although applying lead and lags may cause contraints to be applied. Constraints are a property of a date (start or finish) of a task - for example a task may still have a lag applied but is still scheduled ASAP (e.g. no constraint). 

Hopefully, going forward, Microsoft will ensure correct use of terminology in such articles - thereby avoiding the inevitable confusion imposed by them on users!!