Just get a reasonable grasp of the subject and you'll get it done. WTH does it matter if a certain % of the questions are INS-related? Or polar-stereo? If you've grasped the subject it doesn't matter! a
IMHO those setting the exam questions are pretty nimble and can be reasonably expected to keep moving the goal-posts! Learn the stuff, pass the exams and crack on! Good luck to you all anyway.
bm