my experience, however, the simpler method has never worked on large software development efforts and the costs to recover far exceeded those required to finance the five-step process listed.
--Winston Royce
这个人wiki可以查到， waterfall模型的提出者，人家1970年的文章明确表示，大型开发根本不能用waterfall。
文章链接： http://www.cs.umd.edu/class/spring2003/cmsc838p/Process/waterfall.pdf