Planning fallacy

One of the best book I read during 2014:

Have you ever underestimated how long a task will take? If you have, you are far from alone. The term for this very common phenomenon is the “planning fallacy.”6 This term, coined by Daniel Kahneman in 1979, refers to people’s tendency to underestimate how long a task will take, even when they have actually done the task before. Whatever the reasons, the result is that we tend to be later than we say we will be: later to meetings, later to deliver things at work, later in paying our bills, and so on. Thus execution becomes frustrating when it could have been frictionless. One way to protect against this is simply to add a 50 percent buffer to the amount of time we estimate it will take to complete a task or project (if 50 percent seems overly generous, consider how frequently things actually do take us 50 percent longer than expected). So if you have an hour set aside for a conference call, block off an additional thirty minutes.

Greg McKeown – Essentialism