Test against strengthened skills.
I'd like for a way to have a quick quiz with questions randomly pooled from any skill I have currently at full strength.
I took Japanese in college for several years, but struggled with advanced conversations in Japanese. When I looked back at my education, it was too focused on boxed lessons (i.e. learn it, drill it, test on it, move on, forget it). When I was put on the fly for anything I should know, I couldn't keep up.
When I'm using Duolingo, I can sometimes infer the answer rather than KNOW the answer simply because I can tell what subject I'm in. I'm remembering the quiz and not the language.
That would be nice. I've encountered this problem in all of the languages I've worked with, but it's definitely more pronounced in difficult languages like Japanese. For a while I thought that's what the 'practice' feature was suggesting, but now I think it just selects a lesson at random.