What the pattern is this year, how the marking really works, and how to plan the year. Facts from the bulletins and the papers; nothing goes out before a second person has read it.
Every wrong answer is a map of what you do not know yet. How to keep a mistake book that gets reopened, what to write in it, and when each entry comes back.
Very nearly for Biology, mostly for Chemistry, and for Physics the book gives the ideas while the exam asks for speed. What 'enough' means, subject by subject.