The point of anything. Kept.

Give Crux a YouTube video, an article or a page of text. It writes cards that teach the main points, so you get the substance without watching or reading the whole thing. Then it has you recall each card before showing the answer, and brings it back when you are about to forget it: what you find hard comes back sooner; what you know goes further out.

Each day has a cap, and days you miss are spread across the following week rather than handed back to you in one pile.