> That is the very definition of a waterfall design model. No it doesn't mean that. When you can rely on your data it's easies to code and test than when you h

> That is the very definition of a waterfall design model. No it doesn't mean that. When you can rely on your data it's easies to code and test than when you have to account for every bad data combination. And remove the constraint is easier when you need it, than to add it later. Thanks for the feedback!