So, I took a few months off, and note that I’ve burned a number of kanji that I no longer feel certain about. Rather than simply resurrect them, it would be TRULY useful if the burned list functioned the way the “Answered Incorrectly” list does: if, when you hovered over a burned kanji, the relevant info would immediately pop up. It would be great to instantly see the English and Japanese. (Even better, the English, on’yomi, and kun’yomi.) For now, you have to click on the kanji and open it in a new tab or window, which is a pain.
Okay, figured this out — in case anyone has the same question, you can install the “Self-Study Quiz” script, and it gives you this option (and many more):
Having burned items isn’t related to speed. It just means at least about 6 months have passed since they started. Someone going at max speed wouldn’t get their first burned item until around level 28 or 29.