Variable diag

I just read the Aug 15 newsletter and was confused. It states that variable diagnosis can be paid to a tech with a single set of punches. My take in reviewing this with an AVM is that a tech must have two sets of punches for ANY variable diagnosis payment. One for the component replace/repair, and one for the diagnosis. This scenario gives a clearer definition of repair vs diagnosis rather than just running the clock for both. The question is, how can you pay a "variable time" without punches to substaniate the actual variable time? Just wondering.