I understand that some people really need it, but isn't the point of exam conditions that we are tested on our ability to work under the pressure of time? If someone can't work under timed conditions then they shouldn't get extra time because surely that defeats the point of having exams! It's like giving people with lower IQs higher marks to compensate for their low IQ, when really their exam results should reflect that low IQ (I am in no way saying that people who get extra time have low IQs as I know that is not true - I am just making an analogy).
Someone I know is autistic so he gets extra time. He is in a few of my classes and he works a lot quicker than me and he reads a lot quicker than me too. I often have to read things several times to even begin to understand them, especially in an exam when stress means that concentration is difficult. I don't get extra time or anything and personally I don't think I should because it is something that I am less good at than others and that should be reflected in my exam results as that is what exams are for.