I’m not sure it’s a weird study habit per se, but during this Coronavirus lockdown a close friend of mine picked Korean study back up again to fill time, and we’ve gotten into a nice routine of having almost daily discussions about what new things she’s learnt. She’s described those sessions as being really helpful to reinforce what she’s learning because she’s having to explain them to me, someone who can’t speak any Korean, and I’m able to provide different perspectives with the Japanese equivalents (or differences) in grammar and of course we can both compare against English.
I noticed pretty quickly that it’s been beneficial to my own study because her explanations are encouraging me go back to grammar that I learnt a long time ago to delve deeper into the nuances etc. When she’s a bit further in and more confident in her ability to understand what she’s reading we plan to start a little book club where we read the same thing, her in Korean and me in Japanese, so we can discuss the differences in approach to language used for the same scenes etc. We’re hoping to wrangle in another friend who is learning French so we can get a third perspective.
Otherwise, writing everything down. I struggle most with understanding, not necessarily cultural contexts for words, but words that can be used in different ways than they would be in English - I think my most recent was seeing 落ちる used to refer to failing a test. Whenever I see something in the wild, it goes in a notebook where I can write down the word and the context etc, with an example sentence. It doesn’t necessarily help my retention immediately but I’ll flick through those books routinely to reinforce. Eventually it helps.