I get extra time, I should get a separate (distraction free) room, additional help with notes and the option to type my papers (those who have ever seen my handwriting will know why... ).
If there are accomodations available, use them! They are there to "level out" the field, giving you the "same" conditions as the others, but taking your disability into account.
Personally, I rarely need the extra time, as if there are no distractions I am usually one of the first to leave, but the arrangements help me a lot.
Not having everyone else making a noise, or the invigilators constantly walking about is a real help.
Also having the instructions printed and given to me, rather than read out by the invigilators, that sort of thing.
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The optimist says the glass is half full.
The pessimist says the glass is half empty.
I just want to know who drank the water...