I'm probably gonna get flamed for claiming such a high amount but I genuinally have been working 14 hour days in the library... In that I arrive at 8.30, breakfast and start by 9.30, coffee at 11.30, lunch at 1.30, coffee at 5, dinner at 7, leave at about 10. so thats getting on for about 10 hours of work.
I am however in the middle of my masters finals. theres no way i could have ever done that much at A-level. But when exams really matter and your timeframe is short people get 'the fear'..... which is a terifying yet wonderful period where you have no time to procastinate or stress, you just work your ass off as long as you can to try and desperatly understand the content in the next 48 hours.
And yes I have worked all year at it but when you have exams on consecutive days over a week you need that cramming time to adjust your head to the module. I really hate my uni for scheduling 6 exams in 5 days....