I'm receiving a few good natured jibes from fellow students in a class where I resisted the idea of extensions or exceeding page length requirements. There's two issues there. Given my RSI, I have to be very careful in planning my keyboard intensive activities and I must pace myself. If it's something that will require a last minute crunch, it's probably not something I can do without incurring pain and maybe a set-back. Then there's the variable of content to time. When a Professor extends a dead-line or says, "Sure, feel free to answer that question with 10 pages," while it feels like a favor, it rarely is. To me, it means more typing. For example, how often do they consider constraining the requirement, or dropping a question?
I spent about 20 hours in front of the computer for a mid-term and could not have done that much computer time in the original one week given my other tasks. So in one sense I was glad I could pace it out over two weeks. Also, for students that had other mid-terms, an extension allows them to mitigate the collision of demand. However, one could also spend the one's life working on the exam to "get it perfect," but one needs to call it quits at some point and focus on other priorities. Of course, graduate students are generally work-a-holics and also feel that they are in competition with each other, so they don't often recognize this dynamic. While I love writing, and playing on computers, my RSI and work experience gives me a very pragmatic and cautionary approach to work/typing/pain management.