The value of CPM is more than mathematics.
Proper use of the methodology will help the project team complete projects on or ahead of specified deadlines. But another reason is that parties to a contract know that a CPM can tie arbitrary, capricious, in bad faith or just stupid decisions to the impact thereof.
And so, the egos of the project “team” are nudged to back down, to be reasonable and to act in the best interests of the project. Even if the CPM is flawed, the very fact that one is used will help bring the project in on time and budget.
Those who follow this blog may comment that we are usually all about the mathematics, and the need to follow the strict rules of “physical logic first and then only enough resource logic to make the plan reasonable,” thus giving the project team maximum flexibility in the week-to-week and day-to-day scheduling of work crews.
And if the team becomes dogmatic and too bound to a bad plan the project will suffer.
But the theme works both ways. A properly made logic plan can help a dysfunctional team (of owner, engineer and contractor) yet finish a project on time and budget. But if the process of building even a poor logic plan (or schedule without a proper plan) fully engages these parties, the project may fare even better.
Of course the best of all worlds is to bring suspicious members of the team together, to create a proper and well thought out logic plan, and then to implement the calculated schedule using the strengths of the members of the team to build a project of which all may be proud.
Being able to assist in that experience is why I love our profession. There is nothing quite like driving by a successful project in which we have assisted and recalling the working friendships we had and the obstacles we resolved together.