Most of us who reload use a lot of “once fired” or even “range pickup” brass as part of our regular reloading routine. If you inspect the cases and watch for signs of wear this is a perfectly safe practice that has kept the cost of shooting down for countless reloaders. This even works out at most local shooting matches where competitors can pickup and keep their brass after they shoot. Well, as much of it as you can find anyway. There are really only a few times when following this practice isn’t necessarily in your best interest.
One of the times you might want to use new brass is when you are headed off to a major match. The once fired stuff is great for practice and the local matches but if you are headed off to a major you want to bring your best and avoid a worn out case causing a disaster, even a minor one, on the range. By the time you pay expenses for match fees, travel, hotel, car rentals and food the $60 or $70 worth of brass that you might leave lying on the range is pretty insignificant. Even if the match is local and you don’t incur all those additional fees why worry about a bad piece of brass messing up your match?