Adding engineers to a late project can make it later

 

Major Premise: Sixty men can do a piece of work sixty times as quickly as one man.
Minor Premise: One man can dig a posthole in sixty seconds;
Conclusion: Sixty men can dig a post-hole in one second.
                                                                       - Ambrose Bierce

The Mythical Man-Month recognized in the software engineering world the fallacy that work is arbitrarily sub-dividable and fungible, but obviously Brooks was foreshadowed. 

One man can dig a posthole in sixty seconds becuase he has freedom of movement, no need to coordinate his actions, and can focus on his task.  Sixty men digging a posthole spend more time coordinating, cooperating and avoiding each other, than they do actually digging.  Similarly in other tasks there is an optimal point were people can work together effectively and efficiently, beyond that point you start to get diminishing (and eventually negative) returns with each person added to the effort.

                                                                               copyright 2007 Kerry Champion