I thought 3 hours was the perfect amount of time. I wrote about 5 pages for sections 2 to 4, and exceeded the space provided for the Core Topic questions. I wasn't writing flat out, but I finished with only about 5 minutes to spare. I find it disturbing that people would leave an hour early (20 mins maybe, but an hour!). I mean, you could write about 6 more pages of information in that time, and secure a killer mark. Shrug ... maybe I'm just a slow writer.
The reason why I can't believe you can leave early is because at our school we get told if you leave then you get no result and can jeopardize your HSC. Maybe if you are at a bigger school then you can leave early, I'm at a smaller school so maybe they just like us to stay...
My school is a small school and we wouldn't even try to tell our students that they couldn't leave because we know that they would be appealing to the BOS and we would lose.
Leaving early doesn't mean no result. It might jeopardise your HSC in the sense that you might have written more and so you mightn't get the result you would like in that subject but as for no getting an HSC - no - leaving early won't mean you don't get your HSC.