A dashboard brief often starts with the available data: sales, traffic, conversion, margin. That is useful inventory, but it is not yet a reason to build anything.
The better starting point is a decision. Who needs to decide what, how often, and what would they do differently if the signal changed? Those questions determine the useful level of detail, comparison period, and alert threshold.
Once the decision is clear, some familiar metrics become unnecessary. Others need context, such as a target, prior period, or expected range. The layout gets simpler because every element has a job.
A useful dashboard is not the one with the most complete view of the data. It is the one that makes the next sensible action easier to see.