Lagging tiles report what already shipped, billed, or healed. Leading tiles report what will bite next week: kit completeness, unplanned maintenance, unfilled clinic slots, documents still with customs. Mixing them on one slide produces a peculiar silence. Directors stare at last quarter while the risk sits two cells to the right, unread.
In Mid-year Recalibration Labs we split the script. Ten minutes for lagging, with no forecasts allowed. Then a clean break. Then leading questions only. People who want to “contextualise” the risk with last quarter’s success are asked to wait for finance’s Friday export.
This is not a theology of KPIs. It is a speech design. Human rooms cannot hold two time signatures at once without a conductor. The chair is the conductor. The panel is the score, not the orchestra.
If your current packet interleaves the two, mark the time signature in the margin before you add another chart. Addition is how mixed rooms stay mixed.