Personally, I think the AS History exam is too short. My other subjects have perfect time limits, like English and German. I finished my English exam today with 15 minutes left, even after spending 20 minutes planning my responses to both questions. However I still have further issues. I understand the point is to be able to write essays with the key points straight away to prove you are a prepared candidate, but that is nothing to do with understanding and encouraging interest in History itself. I think this has evolved from a trend in the government with their dilution of examination and the league tables they produce from it.
They are testing candidates on how they can recall events and discerning ones that are relevant, it's like a more specialised General Studies, rather than developing an argument about History and going into riguorous academic depth. The 24 markers do this to a degree, but not enough. There needs to be a longer time limit to allow this depth to be demonstrated by candidates, and the questions need to be more imaginative than 'blah blah says this is important, do you agree?'.
Most candidates who take A levels want to go to university, and I don't think these exams prepare you well for what is required of you. University examinations are double -if not more- the length of these exams. The exams' questions are of poor quality anyway, before one can say there isn't enough time to produce an individual, carefully contemplated response. People can just research mark schemes and regurgitate old arguments. I totally agree with roseroserose. on this, arguments become formulaic and boring when you have to answer as you go.
As for extra-time, there is a huge system in my school where anyone who has problems which can affect performance negatively - and therefore get grades not representative of their intelligence - will get extra time. It isn't handed around freely. If you're a slow writer, it has to be a proven problem that doesn't seem to get better not matter how much you try. That girl who claimed somone at her school apparently said she was a slow writer and got a laptop was misinformed. The examination board must approve, and there is a long process before you can make an application, i.e. tests for your condition. I don't think completing exams has any correlation with being a doctor or a lawyer. Working is a different exercise altogether, it is much more vocational. It is important that students with severe dyslexia/dyspraxia/certain types of autism etc. get an accomodation with this so those unfortunate issues don't discriminate them unfairly.