But he only talks for like 1.5 hours whereas we take 2-3 weeks per topic. I don't get the logic of that... I still have to flip through textbooks if there's something new I don't fully understand.
It's because at school you also need to do the textbook questions. Textbook theory, especially for Maths, can be gotten through relatively quickly, it's the questions that suck up most of your time. And all Dr. He provides for questions is maybe 2 homework papers per chapter which excluding the challenge question can be done in less than an hour for each paper.
Pity, he improved my maths SOOOOO much 
I have no idea how much he has improved my maths. All I know is that my score and ranking for his homework have gone up every week so far.
Maybe it's because I am unmotivated in terms of VCE maths - hopefully this will get better once better topics (ie. TRIG) come into play.
I need to spend more time on olympiad now, seriously... too much VCE bio. Lol I haven't even done homework in school for maths for about 4 years now. 
I was the exact same as you. I never did any work for Maths from Y7-Y10 and I often slept in class. But then the massive jump from Y10 Maths to 3/4 Methods motivated me. It was so strange having to actually learn maths concepts and do the textbook for the first time.