Psychology
Hofstadter's Law and Project Planning Fallacies
Quick fact
Hofstadter's Law is famously self-referential: it states that even when you take the law into account, the task still takes longer than expected, meaning no matter how much buffer you add, you'll still be late.
Why this is interesting
Have you ever promised yourself a project will be done in a week, only to see it stretch into a month? Why does that keep happening, and why can't you just plan for it?