I love mytomatoes.com. As I said in another post somewhere, it helps me to realise that every minute counts, which is expecially important to me as I need to write so much to be done in 6 mths. I like the idea of structured breaks, and this helps stop me procrastinating and skiving off for longer than I should be. It also means that when I concentrate, I really cencentrate and know that the work I've done is solid.
I fluctuate - I find I'm really productive one day, then then take it a bit easier the next day. I average about 12 during week days, but every second day or so I have a big day and do 16 or 18. I do less on week-ends when I have some other commitments. I also use a chat room with other people who use tomatoes, and about 10 sounds like their average too. I'm going into overdrive at the moment, writing up, so don't think I'm typical.
Button, work at your own pace, feel good about what you achieve, and don't compare yourself to other students, too easy to feel others are doing better.