I had a random question about something that has been bugging me. In the progress stats, I'm always about 20 characters and 10 words short of "knowing" all the words and characters I've added. I think I read elsewhere in the forums that "knowing" is based on being able to retain for about 12 hours, before I always figured I had about that many floating around under that time window.
However, I haven't added any new characters or words in about three weeks. I've just been reviewing old material, almost all of which is at a two or three week or longer interval. It seems like if there were still 20 characters under a 12 hour window, I would be seeing them all the time and know which ones they were, but it doesn't feel like this is the case. Am I missing something?