I think you are correct, but your scenario is a good example of something else: Prototyping and "planning to throw one away" (Fred Brooks / The Mythical Man Mon

I think you are correct, but your scenario is a good example of something else: Prototyping and "planning to throw one away" (Fred Brooks / The Mythical Man Month). Of course, but one is not always implementing a totally new system that justifies "throwing one away". Often one is implementing something whose design is well-known enough that one should expect to be able to do it right the first time. Having written one lousy implementation in X months does not mean that the good implementation, when starting over, will take X more months. Sure, but it still takes Y more totally unnecessary months, even if Y is less than X.