Recently, Tom told us about an upcoming book, Mindless Eating, by Brian Wansink. The book is now out, and it's very interesting. Key themes—The amount we eat is usually not determined by how full we are, but by how much food is put in front of us. And, we usually underestimate how much we've eaten. (I highly recommend the book. The stale popcorn story at the beginning is worth the price of admission.)
Can't help but relate this to business—How often do people, out of inertia, keep working on the thing that's in front of them, without questioning whether it's worth continuing? And, would they then underestimate the amount of time that's been sucked up by a stale project?