Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law. I usually take my prediction, multiply the time by

Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law. I usually take my prediction, multiply the time by 2 and add another 1/4 of the time to it. If it turns out to be faster, win-win for everyone. But usually, my guess is quite accurate that way.