In the nick of time.
In customer service, time is everything. A quick response and resolution can set your customer service effort apart from the rest. That means, you can't afford to lose track of pending tickets or responses. With time based rules, you can configure workflows to be triggered when a timed event occurs. For example, agents are notified when a ticket is pending for more than x hours, or when they've not viewed a response for x hours. Similarly, an email can be sent to supervisors if a ticket remains unassigned for more than x hours, or when an agent spends more than x hours in resolving it.