I stopped playing after reaching a bit more than 2000 day streak.
Towards the end I was just going through a lesson as fast a possible before going to sleep. That was no fun and I got nothing out of it.
That's exactly what I'm doing these days, sadly: just quickly sprinting through a quick lesson or two before going to sleep so I can maintain that streak. I've learned a lot from Duolingo, but none of that learning is recent.