This lines up perfectly with my use of the documentation. It really helps quite a lot to do it first, but as the implementation is underway, new scenarios come

This lines up perfectly with my use of the documentation. It really helps quite a lot to do it first, but as the implementation is underway, new scenarios come up and it's often a challenge to go back and update the docs. The new things also aren't something that derails the entire design. In the end, the docs are usually thrown away or transmuted into something useful for other departments.