After travelling to Spain in September and life getting in the way for the end of last year, it's taken me a while to reach the >450h halfway point of level 4 (300-600h).

Rather than detailed points, a few observations:

• Revisiting beginner content (e.g. the horror VR game series) has been useful for showing the improvement in the last 200 or so hours. Comprehension was better, to the point of picking up Pablo using the Spanish version of the English idiom "between a rock and a hard place", which was satisfying.
• Related to the above, native YouTubers are becoming more effortlessly comprehensible. I need to put in more concentration vs an intermediate video where it can waiver a bit, and it's definitely the gist at points, but easier to follow certain native YouTubers - Luisito Comunica, CoreanoVlogs etc - who speak clearly.
• Starting to notice more where there are specifically vocabulary gaps, particularly with podcasts. I find I can often more easily follow a podcast without having to consciously stop myself translating vs a YouTube video / DS, but there are points I encounter a few words where I can't infer the context and lose the thread until more familiar vocab.
• I've watched a few advanced videos and, as anticipated, didn't find them too bad. I considered starting reading and have made a few attempts (Olly Richards' short stories, El Dador on Kindle), but will be holding off for at least the 600h point. While I'm keen to get into reading, I'm not in a rush and have noticed when trying to read more difficult content that I'm definitely not hearing the same Spanish words in Spanish accent voice in my head that I am when remembering words I've acquired from DS.

I've been putting more focus on consciously following the DS videos, and not translating as I go. People have suggested almost a "meditative state" of clearing the mind to keep focus. It definitely helps, and I'm realising I can follow without trying to translate as I go. I find if I'm not paying full attention, it's (unsurprisingly) harder to keep the concentration.

I've found a few DS videos and series where I'm genuinely interested or enjoying it. But still find it easier generally to maintain that level of interest with things like native YouTubers, albeit needing to tolerate more ambiguity.