tipping point.....................

 In knowledge work, when you agree to a new commitment, be it a minor task or a large project, it brings with it a certain amount of ongoing administrative overhead: back and forth email threads need to gather information, for example, or meetings scheduled to synchronize your collaborators.  This overhead tax activates as soon as you take on a new responsibility. . . . As your workload increases, however, the overhead tax you're paying will eventually pass a tipping point, beyond which logistical efforts will devour so much of your schedule that you cannot complete old tasks fast enough to keep up with the new.

-Cal Newport, Slow Productivity: The Lost Art of Accomplishment Without Burnout