I understand that building Use Cases for a specific site or app more often come from a Business Analyst, though sometimes a UX consultant can help to construct depending on the context. Now,What are the differences that a Use case will bring in against a task flow diagram. How use case still be avoided (if so) by building scenarios and user journey models? My question is specifically -
1.Should a Use case be a starting point? Or would you use any UX tools?
2.Would you replace Use cases with something equivalently robust and best? In which cases would you recommend an alternative?
3.What would be those alternatives? If use case not standard "UX tool" or "method" - how would you bridge the gap?