You study as long as you need. I revised 6 hours a day 7 days a week during the full time groundschool and ramped it up to 10 hours a day in the immediate run up to the exams, after the groundschool was ended. That was what I needed and I got the lot first time round. Even now I look back in disbelief at the effort that was required yet at the same time they were some of the best days ever.