I can usually manage 6-8 pages per hour. Depends on the questions and thinking time and everything else. And my handwriting isn't big, but I'll admit it does get messy.
I had a 2 hour sociology exam today at uni. It was three essay questions and I wrote 9 sides. I'd think that's probably about average, that?
In an hour and 15 minutes i can write 12 pages which i did for quite a few of my exams last year...yet in others which i thought i had no idea what i was going on about i wrote about 3 or 4 pages...didnt seem to make a difference with my grades tho still got A/Bs It doesnt really matter how much you write...as long as you can put all relevent information in your answer i suppose.