Keeping my tree golden
How does Duolingo determine when you need to "strengthen" a skill? Is it based on you missing questions on a particular grammar or vocabulary rule in another lesson? Or is a just a timed thing, where every few days it picks a few lessons for you to repeat?
I'm not sure about what way it goes. . . . . I think it degrades the lesson that you didn't do in awhile, but interesting question maybe someone better than me can answer that.. :)
It is based on several different factors including: how many times you've seen a word, how often you get a word correct/incorrect, how long it's been since you practiced a word, how often you hover over a word (peek) for its definition..