Interest will be running no matter what. You won't be able to pay off loans during residency and need a hardship deferral anyways. That said, you are correct that it means 6 months of extra interest tacked on to your total, no matter how you slice it.
As for what to do during the time off... depends. I know of people who land an intern spot in Aussie and then ditch the spot once they match back in the States, taking 5ish months of Aussie intern pay with them (which is ~$20k of take home, give or take). I personally plan on finishing up any research projects I have going on, interviewing for residencies, and then taking a well deserved European vacation for a couple of months after I officially match. Others plan on just vacationing the whole time, researching the whole time, or working in some unlicensed position at a hospital in the states or perhaps more internationally. Ochsner is specifically interested in retaining some students as researchers during that time (with POSSIBLY some paid positions) but that will amount to only about 30ish or so people, likely those who already have a record of research at Ochsner.
So in essence, it is what you make of it. As time goes on, there may be more robust things to do.
