Good luck with finishing off your sketchbook!
Personally I'd be wary of planning things out too much in advance. I think spontaneity can be a good thing in sketchbooks because if you plan everything that you're going to do but then don't feel like doing the thing you have planned any more, you might feel pushed into a corner because you feel like you should keep consistent. Idk if I explained that very well. Of course you're free to do whatever you want with your sketchbook, but I see a lot of people getting really demotivated with their sketchbooks because they treat it like there has to be some finished artwork on every single page, or at least most of them. I think sketchbooks are a place where you're allowed to make mistakes and quick drawings though. That's just my two cents I guess.
I do agree with you though, it's so fun to look through your progress in a sketchbook! I have 4 of the same type of sketchbook, 3 of them are full and my current one is almost finished. They're all 120 pages (60 sheets) and it's so fun to just flip through them and look at old ideas, old studies etc to remind me of methods that I may have forgotten or old ideas. Lots of it is quite cringeworthy, but it also makes me super proud of how far I've come in a year. Yay for sketchbooks!!
