What is a Buffer?
Next, buffers will be strategically placed within the project plan to safeguard the project itself and the most important tasks. The buffer is a certain amount of time placed within a project plan to preserve the success of it. The buffer burn rate tells a project manager how much longer a project is taking over the initial estimated length of time. If a task burns 50 percent of the buffer and only a fraction of the work is done, you know that there is a problem that needs to be remedied. A high burn rate could jeopardize the entire project.
The buffer can also help a project manager control costs. A budget buffer can make your budget both tangible and manageable.
For more information on buffers, read Project Constraints: Time by Joe Taylor, Jr.
Perhaps the most important piece of this system is allowing projects to be completed early and passed onto the next person in line. Multitasking, while it allows multiple projects to be worked on at one time, is does not allow a project to be completed ahead of schedule since there's so much going back and forth between projects. Nothing actually gets done before or even on time.
In Critical Chain, only one project part or task can be tackled at a time. This allows the most "critical" aspects of the entire project to be finished, and the ensuing part of the "chain" to begin. The end of a Critical Chain project is the start of the project buffer.