Mmmmm. When I did the S1 test almost a year ago I was only asked one question regarding speed and Flight level of one aircraft.
It struck me as odd that so much info was provided on the planes that use the sky yet only one question was on the test paper. Perhaps it's just NATS wanting to see just how much you want this and will be impressed if you get this question right.
I'm considering only swatting up on the Airbuses and Boeings (the main types) as my one question was on a Boeing 737, however.....