For all the exams that I did I wrote in 8 page writing booklets. I've never seen a 4 page writing booklet before. So I'm sure the 4 page booklets don't apply to English, Mathematics Extensions and Sciences...lol
Anyway, you're not expected to fill up those booklets. For like question 1 in maths exams you barely use 3-4 pages of those booklets anyway. For English, you can get away with writing 4-5 pages of those booklets for each question and get band 6.
From personal experience, I barely wrote 5 pages of those booklets for each question in the English exams while heaps of people wrote like 2 or more whole booklets for some questions. I ended up getting a higher mark than most of them, so it's really a matter of getting your content communicated in the most succinct way and filtering out the irrelevent crap.
Surely if you were a marker you would prefer to read a short succinct response rather than a very long one after tediously marking hundreds of responses to the same question the whole time...lol Remember that markers have to get through all those responses in a set time limit so they have to work pretty fast. So for longer responses wouldn't the marker be more likely to 'speed read' the material (so there's a possibility of missing some good points) rather than read it properly?...lol