Even within a single culture, different styles of language are used depending on the context and setting. These differences are more than just vocabulary. They include grammar structures, accent, intonation, enunciation, and more.
Proficiency in one domain doesn’t automatically make you proficient in others. For example, understanding news broadcasts in your TL is a different skill than understanding casual conversation. You will need to deliberately target each domain you want to acquire.
Languages are large. According to the Oxford dictionary, there are 171,476 unique words in English. Fortunately, you don’t need to learn 100% of those words to understand a given piece of immersion content. The first Harry Potter book, for example, only contains 6,1851 unique words while the first 10 episodes of Pokemon only contain 1,700.
The fastest way to obtain high-level comprehension in your target language (TL) is to narrow your immersion focus to a small part (subset) of the TL, master that subset, and then expand.
Most domains overlap with one another. This means you won’t be starting from scratch each time you tackle a new domain. If you master casual conversation, then news broadcasts become much easier because there is shared vocabulary, grammar, etc. between those two domains.
The more overlap between a target domain and your mastered domains, the easier that target domain will be to master. As you master more domains, each new domain becomes easier because there is more overlap between what you already know and what you are trying to learn.
As you progress through Stage 2, each new TV show, movie, or book will increase the size of the domain you are trying to master. Pay attention to how wide you are making your domain and avoid hopping around between many domains. The narrower your focus, the faster you will progress.