Can I preface this by saying that I am a complete nerd ...

With my last two subjects, I probably spent at least 30 hours a week on them each. They were masters units, and I did just the one at a time.

With my undergraduate subjects, it was probably closer to 20 hours per week for law subjects, and 10-15 per week for arts.

I did not do every single reading, but I would look at them all to see what was there so I could assess what I needed to know, and do all the questions and all the homework. And I spend ages revising and doing up my exam notes, practice exams, and I spend a really, really long time on essays.

But like I said, I'm a nerd.

Some friends wouldn't have spent more than 60 minutes per subject. Some spent none - they just went to classes, and then bought another student's notes to review before the exam.

HTH.