Scenario where this would benifit us.

Our triage process has a kanban board with three columnns.
Awaiting Triage, Clarification Required, Accepted.
It is not acceptable for something to remain in Awaiting Traige column for more than two days.
It is not acceptable for something to remain in Clarification required for more than 5 days.

Right now the 'age' is useful to indicate when something has broken this SLA, however I'd like the ability to make this more 'in your face' by highlighting the card in a bright colour.

Of course the number of days would need to be configurable per column.