I guess note taking during spare time is considered "revision"... when it comes to year 12, i think notes/summaries are important for easy reference instead or reviewing the entire textbook ~
well for me, making notes is too time consuming and i understand more when i answer questions. Notetaking is should be done during classes... revision and practise questions i do at home...
well this strategy works for me...
writing notes for chem is a waste of time because there are summaries in textbooks (eg "key points" in Chemistry Context textbook) that are already done for you... and especially if u have Excel. I'd rather spend my time practising questions rather making repetitive notes.
well i think ur friend didnt do well in those extension subjects and they were too hard for him/her to handle.
*The friend of yours who did general maths and standard eng, what year did he do his HSC ?