A few hundred hours of listening simply isn’t enough. I have ~800 listening hours in Italian and I still have challenges, especially in certain situations. You simply have to do more listening, as others have mentioned. Every 100 hours of listening you add, is a step up in your listening comprehension.
Probably the key principle to improving your listening comprehension (and the language as a whole) as an intermediate/advanced is to follow the difficulty. If something is hard for you, this is where you can get large amounts of improvement. Obviously, you don’t want it so hard that you don’t understand anything, but you want it to be challenging for you, so you have to concentrate to be able to understand it. Over time, this becomes easier and easier to understand and then you need to find something else that’s challenging.
One of the issues I’m currently having in Italian is that I can easily understand people who speak standard Italian with clear audio and speak clearly. But a group of native speakers in a noisy environment with poor sound quality, when people speak with strong regional accents and switch back and forth with ‘dialect’, it’s very challenging. In order for me to improve my listening comprehension, I need to practise more with such content. As I can’t easily search the Internet for “poor sound quality with strong regional accents interesting Italian podcasts,” my idea is to artifically create this environment. That is, listen to chit-chat podcasts (multiple native speakers speaking over top of each other) with low volume and lots of background noise (as in walking along a heavily trafficked street, in a loud cafe, or next to a construction site with low-volume podcast audio). You are forced to concentrate hard. And in language learning, concentration = gains.
My second method is exposing myself more to the many regional languages/dialects of Italy. It’s not always easy to find such content, but there are several movies and YouTube channels, which I’ve encountered. My theory is that if I expose myself to the dialect, then when they speak accented standard Italian, I’ll better understand them, as I’ll be familiar with the sounds of that region. Depending on the content, I may or may not watch it with Italian subtitles on at the same time.
As @PeterBormann advocates, reading while listening is very effective (especially with increased audio speed, as this increases the difficulty). There will come a point though, where reading becomes a crutch and your listening comprehension isn’t improving as fast as it was before. This is when it becomes too easy. At this point, you should remove the subtitles / transcript and listen to novel podcasts without the transcript. Then when that becomes easy, find ways to increase the difficulty, like studying in a noisy cafe with quiet audio instead of in the silent area of the library.
A final point that I’d like to mention is to select audios with high-density talking. I’ve watched a lot of movies and TV series in Italian, but it’s just much slower in improving your listening comprehension and language abilities than listening to podcasts or talk shows, etc. It works out that the standard movie / TV show has about half the amount of words read per hour than that of a podcast. As a random example, which turns out to be coincidentally perfect, La scuola cattolica has ~7,500 words in the transcript for a 106 minute movie compared to a speech by Alessandro Barbero entitled Usare la Storia per prevedere la futura? has 8,600 words in rhe 61 minutes talk. I.e. 4,250 words/hour compared to 8,500 words/hour. Obviously, more words per hour = faster gains. That’s why increasing the audio playback speed works great.
If you’re looking for interesting content, here’s a list of my favourite content in Italian:
https://www.lingq.com/en/learn/it/web/community/post/4997559