Flag orders that sit in one stage too long

Beyond the promised-date color alerts, I want to set a time limit on each stage and have an order flag itself if it sits there too long. For example, drafts maybe shouldn't take more than five days. If an order has been sitting in a bucket beyond the standard time I set, it should start to flag yellow then red so I can see it's overdue for that stage. That way nothing quietly stalls in one phase without me noticing.