Ask each stakeholder which decision they made last month using analytics. If the answer is none, that tile leaves the board.
One north-star outcome plus a handful of inputs the team can move in a sprint is enough. Volume vanity metrics can live in an archive report nobody is forced to recite.
The lasting artefact is a one-page sheet: definition, source event, owner, review cadence. That sheet becomes the contract between product and engineering.
Two weeks later, check whether the first report used the new language. If not, the lab failed — fix the ritual before adding events.