My favorite bit of this argument is the presumption of honesty, accuracy, or transparency on the part of developers. Someone in the estimation process is always

My favorite bit of this argument is the presumption of honesty, accuracy, or transparency on the part of developers. Someone in the estimation process is always protecting themselves, packing on a little margin, or fudging the numbers. It's nothing to get upset about, it's just normal human behavior, happens in all industries. For this reason alone, I always kick estimates back down and amazingly they almost always come back better-optimized – usually because some trusted graybeard engineer, who has been on both 'sides' of the business, steps in and cleans it up based on his experience.