I created this approach at left a while ago and use it with great success. It’s simple and conducting it over two days is asking a lot but that is when it is most effective, splitting planning and execution work. Although focused on technology adoption and execution here, its overarching purpose is driving business value and could be applied more generally in that vein.
The use case is one of the fundamental building blocks of the workshop in terms of output. Find out more about use cases in my post on them here: Enterprise technology adoption – Use cases are the currency of success.
The point of the fish part of the diagram as explained in the blue text is to encourage open, exploratory thinking in the first part and closed, action oriented thinking in the second. The second day is focused on pure execution oriented planning work.