I do something similar. My method is always to try and fit everything I need for an exam on a single A5 sheet of paper, as if I could take it into the exam with me. The first 5 or so drafts I'd never be able to fit enough on, so with each iteration I make the writing smaller, or work out a pictorial code, or condense my explanation of a method to squeeze on as much as I could. By the time I've finally managed to fit it all on one side of paper, I've thought about how to compact the information in so many different ways that I could recite everything on the paper without it. Repeat that process over the course of 3 or 4 days with plenty of sleep, and it's stuck.
I've got all of the final renditions of each sheet I've ever done filed away. It's always quite entertaining showing people my notes, because they're a completely indecipherable mess of words, numbers, cryptograms, symbols, scribbles and colours. Imagine a sort of Chthonian cult literature. It makes me look insane - but I can still go back to ones from years ago and know what it all means.
I relate to your comment the most in any discussion about notes. Although I don't follow your method always, since I know I will throw out my notes and never see them again, sometimes when I was bored I would do my notes intentionally cyphered and illegible. I wrote over every sheet fully two or three times, in the nooks and crannies and in the spaces between words. Somehow the learning outcome was better because my boredom was lifted.
This was my study mode throughout HS & (somewhat) through college. It really does work, even though I had no idea why I started that way. And my final editions were just as indecipherable to the outside world.
I started when one of my teachers allowed us to take said A5 sheet of paper into my A-Level mock exams. All the class did well, as we had this lifeline. Next exam we were given the same instruction but this time, unbeknownst to us until we walked in, our paper was taken away from us at the door. We were absolutely furious; until the teacher later showed us that not only were our marks all but identical to that of the exam where we had the paper, they were significantly higher than the exams we had before the whole cheat sheet debacle. Basically he tricked us into revising effectively. It's a technique that's stayed with me to this day.
I've got all of the final renditions of each sheet I've ever done filed away. It's always quite entertaining showing people my notes, because they're a completely indecipherable mess of words, numbers, cryptograms, symbols, scribbles and colours. Imagine a sort of Chthonian cult literature. It makes me look insane - but I can still go back to ones from years ago and know what it all means.