I have just completed my French tree!
After 768 days, 3570 lingots, reaching level 25 on duo lingo.com (but level 26 on the duo lingo app!), I am happy to say I've joined the club of all those who have gone before me, to complete a tree! Still have a long way to go, at only 55% fluency, but I am eager to continue on!
You are obviously a much quicker learner than I! It seems to go by points to achieve the next level, and I didn't progress to the next category til I felt reasonably comfortable with what I was currently on. For me, that was every day for over two years! But I finally did it!