You're right about it being different for each person and also for different disciplines, so maybe in my area what my supervisor is expecting is possible (if I keep telling myself that it might seem less daunting !:$ ). I guess all I can do is write at the pace that works for me, whatever that ends up being, and make sure I spend enough time on it that it's a decent body of work that reflects all the effort that's gone in to the project so far. My supervisor wouldn't want me to rush it just to get done in 3 months, he'd rather it was good, but he does still seem to think that 3 months is long enough to produce a good thesis. Hmm, I should stop stressing about how long it will take, and put more of my energies in to actually writing, and resign myself to it being finished when it's finished, whenever that may be! :-)