Some interesting posts guys and gals. I too used to instruct and regularly got students onto 121.5 to do the practice pan routine - personally, I thought it was invaluable experience for the student bearing in mind how tentative most were on the RT and ultimately, a call to 121.5 could save their bacon (CFIT) or avoid a CTR/CTA infringement. Clearly this training process needs to continue but a discreet frequency sounds like an obvious solution.