I have not been to Nationals in 2 years but I doubt if the patterns have changed a lot - still basically a sport pattern. This means that you really need to shoot all spares with plastic. This doesn't mean you won't get lucky and find an area that allows playing a hook at any spare, be it left or right sides for a lefty or a righty, but the odds are against it. I have seen tons of people, good bowlers, throwing their normal house shot hooking spare ball at spares and missing tons of easy 1 and 2 pin spares. They get very frustrated.VERY quickly. Do yourself a favor and start practicing using plastic/polyester at all spares, left side and right side. It will make life at Nationals much more satisfying.
"None are so blind as those who will not see." "Some bowlers are crazy as pickled cats."