No, poor move IMO. If you think you need this much revision for an amazing set of grades, then fine, work hard. I know it works for many people, working hard pays off. But, 9hrs is too much. Maybe 6 as a target, with anything over as a bonus?
I'd also do one subject a day instead. Plus, I doubt reading is going to do a lot really. I'd write notes, then maybe go on to doing PPQs, and then work out what you didn't know and go over it from your notes again. This will mean you'll be aware of what you need to know for exam in terms of the key parts of the syllabus, whilst the process of writing it out will be beneficial.