As a tip for writing fast under intense deadlines, however, the adage is not as useful. The idea of composing quickly is based on creativity, not criticism, so writers who are planning and producing that first draft should take a no-holds-barred approach. Say as you're writing the first draft of a proposal for upper management, a compelling but unsubstantiated idea pops into your head. Why leave it out so early in the writing process? Write it down and flag it as a point for confirmation. Why risk deleting and forgetting it now when it can potentially lead to other great ideas to support your message? You can always strike it later if need be.
How to Write Fast Under Pressure examines this and numerous other tips for the business and technical writer. It is available in print and electronic formats.