Such an easy statement: design for your audience. In reality the audience is hardly ever straight-forward and limited to one group or person with clear needs. And also not uncommon: you design for one client, but the dashboard gets used by many others who you never intended to even show this dashboard to (you would design a new one specifically for them right?).
This is a good piece from last year but as it became very applicable at work last week I wanted to review (and re-share) it: http://seeingdata.org/design-audience-mean/