I think for every JET, not matter their ability, language is a great and consistent battle.
Even if you can speak well, kanji are a minefield. While I don’t use a dictionary everyday in Japan now, most days I do. And I either consider a victory or day of not enough Japanese conversation if I don’t use it. There is always something that crops up where I need a little boost to work out what it is that is going on. Language, particularly early on was a stress for me. I didn’t really study much in the lead up, and so the first 2 months or so were mostly me just getting used to speaking and using the language regularly again.