The right data structure is not easily definable. True, there are ground rules. For instance, tall data is generally better than wide data. A wide dataset with lots of columns can be difficult to work with, whereas the same data structured in a tall format with fewer columns but more rows is usually easier to work with. But this isn't always the case! Some business questions are more easily answered with wide data structures, and that's the crux of the matter. Business questions determine the right data structure. If one structure answers all questions, great! However, your questions may require multiple data structures. The pivot feature in Tableau helps you adjust data structure on the fly, in order to answer different business questions.
Before beginning the exercise, understanding the points in the following information box will be important.