There seems to be a little bit of mass hysteria...
Keep a cool head and everything is going to be fine! Regarding completing all the tests in the time allotted; my own opinion is that practice makes perfect. I've did about 8 different aptitude based selection processes and NATS is by far the hardest, but I still managed to complete all the tests in the time given. If there's one in particular bugging you, skip it and move on. It's better to do three others and get them right than sit on one that you're not sure about.
I have heard (can't comment on the truth of it though) that it's not how many you do, but how many you get correct of the questions completed... Truth or not?
Obviously, do one, get one right = 100%, but they're not going to accept you!
