Originally Posted by Werewolf

Answer 1: that's totally up to you, first do this practice with only that subject which you consider difficult. if you find it useful then extend it to your other subjects as well. And i think 10 past papers are more than enough to outline the complete syllabus of any subject.

Before Answer 2, i must introduce to you an english term,

OSMOSIS: the gradual, often unconscious, absorption of knowledge or ideas through continual exposure rather than deliberate learning.

Answer 2: After you complete making the list of questions by reading 10 past papers, you need not to do anything because, thanks to OSMOSIS that, by that time you would have already grasped the complete framework of the syllabus of respective subject. then your approach would be more professional rather than that of a newbie. start studying (guided by that list) and you will feel the difference.