Dashboards are decision tools
A dashboard that displays 47 metrics but does not help anyone make a decision is not observability. It is decoration.
Three audiences, three dashboards
Operators need real-time health: Is the system working? Is anything degraded?
Engineering leaders need trend data: Are we getting more reliable? Where are the chronic pain points?
Business leaders need value translation: What does this system cost? What revenue does it protect?
Serving all three audiences on one dashboard produces a cluttered screen that satisfies nobody.
The decision test
For every metric on a dashboard, ask: "If this number changed significantly, what would we do differently?" If the answer is "nothing" or "I don't know," the metric does not belong on the dashboard.
A good dashboard makes one important thing obvious. A bad dashboard makes everything equally visible, which means nothing stands out.