We currently mark most papers in a centre - such as Homebush - but that is changing to more and more being marked at home e.g. the core topics in both histories have been home marked, online, for a couple of years now.
We mark for four hours a night - 4 - 6.30 and 7.30 - 9.00. There is a broad expectation of around 12 - 15 essays an hour but that isn't rigid - so that if you don't manage that, but are accurate with you marking (and not really, really slow) the marker will be fine and some nights it just isn't possible to reach 48 due to length of responses, or difficult handwriting or for some other reason but the next night could see you have some really easy to mark centres and so could mark 70. On Saturday's it is a 7 hour marking day.
Please can I set your mind at rest about the 'not bothering' comment. In all my years and talking to many, many other markers over the years the one thing that we all say is that we do try to give as many marks as possible to all students - remember we are teachers ourselves and would like to think, if we have a student with difficult writing, that the teacher's who get out students will be given fair consideration and we do that for the scripts that come across our desks. We are professional in the way that we approach the marking and really are trying to justify giving marks.