What is the time difference in the slow cooker for high versus low?

The vast majority of slow cooker recipes have instructions for both low and high settings. But what is the difference between the two in terms of cooking time?

When you are cooking in your slow cooker, it works out as roughly one hour cooked on the HIGH setting is equal to two to two and a half hours cooked on the LOW setting.

Also see What temperature does the slow cooker cook at? for specifics on the exact temperatures it cooks at.