I've had similar experiences with speed of learning when I visited language courses in the relevant country abroad. And now here living in Japan too. You're right, though, they kind of stop teaching you after a while.



If you already have a decent level of Russian, maybe you could try the textbooks Russian students use?

I have some schoolbooks that were written during the Soviet Union. The propaganda is distracting but sometimes it's so blatant that it's funny. I need to look for something newer.