Re: my previous toot on keeping track on reading, my KOBO reader just asked if I should check some of the books as unread because they've been sitting at 1% for a long time. 3 out of 5 of those books listed for my review are ones I already read, but I must have accidentally opened it again so the progress reset to 1%.
It still took me about full 10 seconds to recall if I've read them or not. It would suck if I didn't think I have read them.