True. I have heard that. Although perhaps that strategy only works if you don't check in. I would think that you can't get through security with an eticket itinerary without checking in.
The strategy only works if you do check in as you need to get the boarding pass to get past security. You can a refund on a ticket after you've checked in for a flight without an issue. I'd just highly suggest calling before the flight departs just to be safe. Not only will that make sure you get the refund but then youll also be opening up a seat that could possibly go to a stand-by. Also at least from what I've been told, the ticket only goes to USED after the flight has been flown.