My take, for whatever it's worth, is that it's YOUR book, so you can count whatever you want.

If it feels like it's cheating to you, though, it probably is. Personally, if I do something like a freewrite to help me figure out how to write the next scene, then I don't consider it part of the writing goal, even though it's related. From what you wrote here, this seems more like a "companion workbook" type of situation, so I'd say it's up to you whether it counts or not.