The board
Stages that mean something, and a clock on each.
A card that has been quietly sitting for three weeks looks different from one that moved yesterday. On most boards it does not, because somebody opened it on Tuesday and the system counted that as activity.
Follow-up
Where the money is actually lost.
Rarely the top of the funnel. It is the consultation nobody called back, the quote nobody chased, the financing application nobody finished.
Each of those is a stage with a clock. A follow-up list somebody maintains by hand decays in a fortnight; a stage with a clock does not.