A while ago, we had a new customer move into the "most intensive known user of our product" position. To help make sure they'd be happy with their purchase, I made a new load scenario.  This one models the new customer's usage patterns, with test compression so that (1) I push the SUT up near its resource limits, so I drive the system far harder than the customer ever will and (2) 2 hours of my load scenario is approximately the same amount of traffic as a normal working day for this customer.  So, a weekend run of this scenario gives me the equivalent of about 6 weeks worth of traffic on this customer's installation.

I won't rerun this scenario too often - this customer's usage patterns are a bit unusual - but I'm glad that I have it canned, and that it appears to be a reasonable model of this customer's usage.  I hope to build more scenarios that I can reasonably name for particular customers (or classes of customers).  I've got no objection to generic tests, but there's a certain warm feeling I get from knowing that a particular scenario covers behavior that I *know* specific users value.