» Healthcare.gov and the Gulf Between Planning and Reality Clay Shirky:
Like all organizational models, waterfall is mainly a theory of collaboration. By putting the most serious planning at the beginning, with subsequent work derived from the plan, the waterfall method amounts to a pledge by all parties not to learn anything while doing the actual work. Instead, waterfall insists that the participants will understand best how things should work before accumulating any real-world experience, and that planners will always know more than workers.