According to this reasoning you should set targets based on expected time, not &quot;median&quot; time. You&#x27;re saying the tail of &quot;completion time&quot; is long, and so the median is a poor estimator for expected time. But if you actually knew the distribution of times for task completion (which is implied if you know the &#x27;median time&#x27;), you could simply use the expected value of this distribution and your projects would then tend to complete on time.<p>I don&#x27;t think this is the correct explanation. I think it&#x27;s far more likely that (1) people don&#x27;t know the true distribution of task times, so estimates are just crap guesses based on hubris, what managers want to hear, etc., and (2) scope creep.