How the five picks are chosen
The list is not random and it is not simply your lowest scores. Each topic you have quizzed gets a next-review date based on how well you did: a score of 90 per cent or more is not shown again for ten days, 80 per cent for six days, 65 per cent for three, 50 per cent for two, and anything lower comes back tomorrow. Topics are then ranked by how weak the score was and how far past that date they are.
Reviewing something just as you are starting to forget it strengthens the memory far more than reviewing it while it is still fresh. That is the spacing effect, and it is the reason a weak topic comes back tomorrow while a strong one waits a week and a half.
Getting five out of ten tells you exactly which half of a topic to reread. Getting ten out of ten tells you nothing you did not already know. The uncomfortable score is the useful one.
Where this is stored
Your scores live in this browser's local storage under keys beginning with mskprod:. They are not sent to a server, they are not shared, and no cookie is set. That also means they do not follow you to another device or survive clearing your browsing data, and a private window always starts empty. You can wipe everything at any time from the privacy page.