Use Cases: Too Much or Not Enough?

Use cases are an effective way of capturing business and functional specifications. In fact, coupled with user interface mock-ups and wireframes, use cases are typically the key constituents of a business and functional specifications document. Use cases often expose dependencies and workflow paths that may not otherwise surface. For all their worth, use cases are time consuming to write. They tend to be bulky and can be repetitive. In fact, we have found there are diminishing returns with producing ever more use cases for a given system. The question is when is not enough and how much is too much? We generally produce detailed use cases around key subsystems such as authentication/authorization and wherever one application interfaces with another (such as when web services are used for example). In such critical or complex areas, there is value in investing and writing detailed use cases. Elsewhere, we have found that it is often more effective to focus on written documentation and mock-ups.