I independently stumbled upon this same system. It sounds like the author takes it further than me (I don't create notes for routine/repeating tasks, and don't break them down so much—in a typical day I only complete around 2-3 notes).
I've used sticky notes for years, but ~6 months ago added the jar (prior to that I just recycled them). It helps to have a visual reminder that I'm making progress over the long term, even if it doesn't feel like it some days.
My current jar is just about full and I've been debating what to do with it. Save it as desk art? Find a bigger jar and transfer the notes? Burn them in a cathartic ritual? I'm open to suggestions.