I have definitely not finished the entire tree so take my point of view with a grain of salt. I actually like using duolingo as well…but sort of as a supplement. It kind of introduces me to new things that I don’t find in other places, which is why I use it as a daily part of my studying schedule.
I try and do one of the levels every 5-8 days or so, basically my own sort of SRS system. I try and not worry about the gamification aspect of it like the leagues because I don’t want to be pressured into using it . Minimum I do maybe 4 a day, which is the highest tier of point goals at 50 pts. Then maximum, if I have extra time in my day or just want to do a little more I go ahead and do that, but I don’t make myself.
I like using a lot of different things when I study. So far it has introduced me to a few words/phrases here and there that I have not been presented with yet in my other studies. The other things I do being wanikani, I make myself a sentence of the day and get it corrected on hellotalk, I have an N5 vocabulary book I study, Try N5 and Nihongo So Matome N5 workbooks, I also do Kanji Kentei practice workbooks and kanji writing practice, I usually do a Pimsleur lesson on the treadmill, and then I listen to a podcast on Japanese Pod 101…I know that sounds like a ton but I spread it out through the day so I don’t notice it. A lot of multi-tasking…haha!
With me specifically, it helps to use a lot of different learning applications, because if I learn something in one and I am confused, a week or two later it will pop up in a different one, explained or presented differently and it clicks in my head!
TL:DR I would use Duolingo, just not put too much pressure on it, just use it as a way to do a minimal amount of study with those random moments in your day when you have a minute or two, that way you can still be working toward your goal of Japanese without sitting down for huge lessons, plus now that they have the mini lessons (lightbulbs) in there they are great little reads for the sections on how to use grammar properly in small easily understandable sizes instead of a huge textbook explanation! Hope that helped a little =D がんばってね！