There is actually a nugget of thought in the article beyond the explanations you always hear (and which make up all the comments in this thread as I&#x27;m writing this): Even if you base your project schedules on accurate estimates of the median time required for each step, you will still be behind schedule for most projects.<p>The reason is actually quite simple: when things go well, they can only go so well, but when they go bad, they can go <i>really</i> bad.<p>Or, in a more quantitative way: while each step of the project will be equally likely to take longer or shorter than median, the steps that take longer can take <i>much</i> longer, while the steps that go faster only have a limited potential for balancing out the delays.