mmm... I disagree
I didn't do a shred of work throughout the year, I havent even completed a single excercise from the book, yet, I got top sac rank.
It's not about how much work you do, its about how well you understand concepts. And its not as if "yeah i understand it" is good enough, if you really understand maths the same way you understand english, where letters and numbers are more like words that will always make logical statements and working with whats true and whats not - you literally can do specialist with 2 hours of work for the year and come out on top - I did it!
Remember, its not how much work you do (you'll peak a few exams in anyway and wont make any progress from there so theres no point in doing more than 10 exams tops), it's about how well maths makes sense. And you really need to fill in any hole you may have at all!