Two issues for me - not enough room in my head for all the styles to be memorized; not a young enough palate to recognize the distinctions well enough any more. So if I pass at all it will be by a bit of luck. I can judge the heck out of beers when I have the style guidelines in front of me, but take that away and I am like a blind librarian trying to restack books by feel.
I don't understand why the test is set up the way it is, since no (or very few) judges judge without the style guidelines sitting in front of them....but hey, I don't know it all. They do the bar exam and doctors boards closed book, so maybe it makes sense to do it that way. Enough of my rant! Back to my Helles.
As much as it doesn't make sense to test that way, if you let people test open book then almost everybody would get a perfect score. Then you're just testing to see who will spend a few hours reviewing the guidelines and another few hours taking the test. That sets a far lower threshold to become a recognized judge. Memorization as a proxy for comprehension isn't perfect but it still sets a better standard.