Via Junto.Investments:
Work expands to fill the time available for its completion. It was first coined by Cyril Northcote Parkinson in a humorous essay for the Economist in 1955.
Primary origin: Cyril Northcote Parkinson
Projects expand to fill the time available for their completion.
So even if the project with a two-week deadline could be finished in three days, you’d still tend to use all the time you have.
And the additional time you spend wouldn’t even improve the quality of the work.
Hence, people waste a lot of time and effort –without realizing it– to get the same outcomes.