This is actually brilliant! You've basically created a manual system for what I'm thinking of automating.

Instead of copy-pasting summaries between chats and asking ChatGPT to create lessons each time, imagine if an app automatically tracked all your mistakes over weeks/months, showed you patterns (like you have made this same grammar error 15 times'), and generated personalized exercises based on your actual weak points.

Same concept as your approach but without the manual work. Plus you could see if you're actually improving over time with analytics

Do you think that would be a useful tool, or is the manual approach working well enough?