If you listen to a news anchor you will understand more than if you listen to a movie. And I would guess a stand up comedian is almost impossible to understand because of the high tempo and advanced humor. In movies it is a lot of slang and dialects. You know in English they have a lot of shortened words, like "can't", "I'm", "it's" etc. We have shortened words in Swedish also, but not as much as in English, and we very rarely write the shortenings. So when someone in a movie says a shortened word the subtitles most oftenly writes the full word. Therefore it can be difficult to se any connection between the heard word and the written one. And quite often the subtitles omit whole sentences. Not in documentaries, but in tv series and movies. Pretty common shortened words are "Jag funderar på't" = "Jag funderar på det" (I am thinking of it); "Jag skiter i't" = "Jag skiter i det" (I don't give a damn); "busschaufför'n" = "busschauffören" (the bus driver). When shortening a word one syllable is taken away.

Hi, a continuous exercise is the only trick that works. You migt listen to News, as the Journalists' language is usually more clear to be interpreted, than in movies( slang, noise, emotions) However, you might also make a specific work using songs, I mean "Listening comprehension", you try to write down the lyrics, you repeat, ... This is a real effort so you will surely get a trained ear within a month. Rhythm... I know what you mean, but no other way than "full immersion". Besides, you might also have a look on Swedish Toponyms and study them: this should make you find some very "intimate", deep aspects of that language(= dialects). Moreover, if you listen to a lot of Swedish before going bed, can't you "play" a "swedish speech flow" in your mind? This usually helps me to relax. https://www.svtplay.se/