Like Goldratt's book The Goal, Critical Chain is written as a novel, not like a project manager's how-to guide.

The commonly accepted principle is to add safety (aka: pad or slop) to generate a task time length that will essentially guarantee the step gets completed.

He asserts that estimates for a task are based on individuals providing values that they feel will give them an 80-90% chance of completing the step, these estimates are further padded by managers above this person creating a length of time to complete a task that is excessive - as much as 200% of the actual time required.

This predisposes the people on the project to consume the time estimate by: The book presents a primer for Theory of Constraints.

This is done in the form of a lecture by a professor who has recently returned from a sabbatical at a large conglomerate that uses the Theory of Constraints.

The book enumerates the five principle steps of the Theory of Constraints: This philosophy keeps the cost and throughput models at odds with one another since the subordination process necessarily decreases efficiency.

To illustrate, the book uses an example of a steel mill with significant production problems, excess inventory and cost issues.

The flaw in the measurement is that not all material takes the same length of time to produce and not all work centers have the same throughput.

This concept claims that one must ensure the resource bottleneck on the critical path is always busy and stays focused.

This requires developing a prioritization scheme for the resource to determine the correct order to do work (i.e. proportion of the project buffer remaining).

[2] In addition, a number of academics have studied Critical Chain Project Management and shown that while the packaging of the content is novel, the ideas are not necessarily original and in some cases, not advisable.