I think I’ve seen a joke usage as well, but otherwise mostly see it when a less common word is used and they want to keep things clear.
The case that immediately comes to mind for me is アグレッシブ烈子, when the 部長 is rapping and the subs want to make sure the audience knows what the English word that he uses means.
It lets you know what he means with the kanji, and shows what he’s saying in the moment with the katakana.