Comment by MathMonkeyMan

I wonder if there's some conservation law for "concerted mental effort." As if by spending time and energy on the often exasperating task of keeping documentation relevant, you reduce the time and energy required to comprehend the system.

You're right, it is a matter of culture and discipline. It's much harder to maintain a consistent and legible theory of a software component than it is to wing it with your 1-2 other teammates. Naming things is hard, especially when the names and their meanings eventually change.