It depends really, for example if you aren't doing say methods, then that opens up two slots, and you just have to change the names around and read the "setup" page. You could copy a sheet by I think it may not get included in the predicitions and statistics page. If I had the time (I don't really atm, should be writing a lab report right now.....) I could have a look at it and try to include it, although I don't remember half of how I set up the groupings/lists linked to the cells, it ended up quick complicated in the end, so I probably wont get to have another look at it.
The reason why I only made 5 slots is because of English, kinda because I didn't fell that I would get enough english exams done to make it worth putting it in, that was me though, didn't account for it. So if it doesn't fit, then I'd suggest excluding english in one and say, making another copy of the file, clearing each sheet out and just filling one up for english. Sorry about that. Also note that the predicition is just a
prediction, there is no guarentee, its more there just to see if you are improving or staying the same, and too see which sub jects you need to work on more.
Hope that helps