This is an important rule: a good design is one that changes customer behavior for the better. - Eric Ries

Peter Drucker said, “There is surely nothing quite so useless as doing with great efficiency what should not be done at all.”2

Because startups often accidentally build something nobody wants, it doesn’t matter much if they do it on time and on budget.

This is one of the most important discoveries of the lean manufacturing movement: you cannot trade quality for time. If you are causing (or missing) quality problems now, the resulting defects will slow you down later.