I am wondering if it is possible to "finish" Duolingo. By this I mean that all the lessons show as completed (yellow) instead of incomplete (various colours). Two days ago I checked and I had 20 "incomplete" and yesterday there were 32 "incomplete". I finished through the tree over a week ago, but I can't seem to "complete" the lessons as they keep showing up for a re-do. I am now in level 16.
Yes, it is possible to have all the circles gold for a period of time. However, you need to practice daily in order to keep it that way. This is a popular method for doing so: http://gregreflects.blogspot.com/2014/12/how-to-make-gold-duolingo-tree.html
I do a few lessons "untimed" , but after that I use the timed practice for the remaining weak ones. This allows me to make all sections gold in a shorter period of time. (plus it makes your brain work faster.) You also will never "complete the lessons" as there is no end. Your tree will always decay. Each individual decides when the lessons no longer benefit themselves. I achieved level 25 in Eng-Fr , but I have not mastered all the material. So it's on to 40K XP for me.
Ah, I now understand. I am at just under 10,000 XP. I started at advantage in that I studied French in school from 10- 18 years old and lived in Montreal, which has lots of French speakers. Still, I hadn't used it in many years to this has been a refresher course. I have found that using the "strengthen" is very helpful to re-gild. I will see how that goes.