Plans that people rigidly adher to even though the information they were based on is completely outdated are pretty bad. But know what's even worse? Having no

Plans that people rigidly adher to even though the information they were based on is completely outdated are pretty bad. But know what's even worse? Having no plan at all, or just a vague mission statement. Because then you have no way to answer the question "what do I do next and how do I know it's finished?", and you end up yak shaving, turd polishing, working at cross purposes and just plain killing time, often way past the point where the project cannot achieve its goals any more and just lacks someone with the courage to kill it. To be useful, a plan has to be updated regularly.