No, it works for anything. The key that people misunderstand is that if the task is really uncertain, you're allowed to give a really wide range. In fact, you'r

No, it works for anything. The key that people misunderstand is that if the task is really uncertain, you're allowed to give a really wide range. In fact, you're supposed to -- that's the only way you can be correct 90 % of the time. As a concrete example, I recently estimated "somewhere between 1 week and 4 months" when asked about an semi-well specified feature because I felt there's a 5 % chance it's done in less than a week, but even under pessimistic assumptions, there's about a 5 % risk it takes longer than 4 months. When asked about a larger, unspecified projects a few years ago, I didn't hesitate to respond "between three months and 15 years". Sometimes that's the best you can do due to the uncertainties involved. It sounds useless, but it's really useful to have a quantitative measure of the uncertainty.