I don't know. Having TA'd during an exam with the disability cases, I can see your point (nothing looks physically wrong) but generally I find that they're give

I don't know. Having TA'd during an exam with the disability cases, I can see your point (nothing looks physically wrong) but generally I find that they're given far too much time anyway, they seem to finish within a reasonable timeframe. If your exams are written in such a way that they're completely time-dependent anyway, you have bigger problems with your examination procedures.