I Conquered the Korean Tree!
Wow, I was generally fluent in Korean and the later lessons of Korean still had a few new words! But that doesn't really matter, because I finished the Korean Tree!
Now all I care about is getting to level 25, but thank you so much Duolingo! <3
You should not worry about levels too much. You should worry more about learning everything you can from DL, because, as you might have already noticed, Dl can't teach you a language.
Although, I have to admit, getting to lvl 25 or completing a tree makes you feel really good. Especially when you start getting a bunch of friend requests and likes on your comments xD.