Brook's law
An outrageous oversimplification that states "Adding manpower to a late software project makes it later"
Brooks's law is an observation about software project management that "Adding manpower to a late software project makes it later.".
It was coined by Fred Brooks in his 1975 book The Mythical Man-Month. According to Brooks, under certain conditions, an incremental person when added to a project makes it take more, not less time