I'm up against around 200 people for English Advanced and around 200 for English Extension. And there are almost 170 spots open for Chem, Phys and Extension Maths LOL
Funnily enough, this is was pretty much what my English teacher said. She believe that the reason so many people in my school preferred 4-Unit Maths was because there was a 'right' answer and 'wrong' answer. You could study hard and guarantee marks, whereas in English, your marks are subject to...
You could try summarize what you learnt into notes every weekend/Friday. Dedicate half an hour and that means half an hour less of studying later on. Setting goals also works, as it can help motivate you and give you something to push for.
Personally, I used to only start studying 2-3 days before exams and get average results. Nowadays I give major exams about a week of prep time. Also will1997 is right, they can only test things in the syllabus.