I started learning Japanese a while back, and studied slowly for a few years.
Then I fell off studying, but kept using it recreationally. I didn't pick 1 medium and insist on it because I have a wife that doesn't speak Japanese at all and that just doesn't work.
But I do still use it occasionally for games, anime (with English subs), manga, and sometimes live TV. It's pretty seldom, but it happens.
After a few years of that, I rejoined a Japanese meetup group locally for reading a Manga with them that's above my level. I'm realizing that I'm basically where I was when I stopped studying. I haven't really lost anything.
My point is that I don't think you need to be extreme to maintain. Just casual usage across different media is enough.
Then I fell off studying, but kept using it recreationally. I didn't pick 1 medium and insist on it because I have a wife that doesn't speak Japanese at all and that just doesn't work.
But I do still use it occasionally for games, anime (with English subs), manga, and sometimes live TV. It's pretty seldom, but it happens.
After a few years of that, I rejoined a Japanese meetup group locally for reading a Manga with them that's above my level. I'm realizing that I'm basically where I was when I stopped studying. I haven't really lost anything.
My point is that I don't think you need to be extreme to maintain. Just casual usage across different media is enough.