Hello!
I finished 3 hours of listening with a combo of audiobooks and YouTube in the last two days, and 1 hour of shadowing.
For the past two days when shadowing, I didn’t focus on getting my pronunciation as perfect as possible, but instead focused on listening to the speakers vocal dynamics and pitch as closely as I could. When I repeated after them, I paid attention to my breath and how high versus low pitch “feels” physically when I make sounds. I guess in short, it was kind of an exercise in mimicking prosody.
I did the first 30 minutes yesterday using an audiobook with a really clear narrator and the second 30 minutes today using a YouTube video where the speaker wasn’t very clear and mumbled a lot and the mumbly video was ironically easier to shadow with. 
The speech was slower and more natural and I could also just mumble through the mumbly parts. 
Anyways, I felt like that way some of my most effective shadowing yet! I had a lot of learnings from it already after just two days! First of all, trying to mimic the vocal dynamics of the speaker while using mostly correct pronunciation (but not trying too hard like I said, I just tried to be natural and self correct here and there if I felt like vowels were shifting away from where they were supposed to be or something) was tricky! I mentioned a few days ago that it feels like I use the back part of my mouth way more as a kind of focal point (?) where the sound comes from, and combining that with breath and pitch was interesting. This is kind of obvious when thinking about it now, but improving your pronunciation is all about how you project sound and there is so much to it!
Another thing was related to “feeling” pitch. This also feels obvious too, but I never actually sat and paid attention to this before - of course there is a difference in how the vibrations feel when you’re singing or talking at different pitches. When stepping up in pitch, I can feel the sound vibrations coming out from higher up in my face/skull almost around my nasal cavity. I experimented with that, listening for the speaker’s pitch and those moments that sounded similar in sound quality to my vibrations and then played around with my own voice. It kind of felt like doing that unlocked a new level of being able to hear and perceive pitch more reliably, which is really exciting!
I will keep doing the same practice for the rest of the week since I want to further dig into the things I’ve been learning from my experiments, but I think I will regularly cycle around between different focuses like specific sounds, prosody, pitch etc. and see if I start noticing overall improvements over the course of the month. I love a good experiment! 
Besides that, another thing I learned is that it’s great to simply put on music or enjoy the silence after setting an insane goal of 80 hours for myself last month. There is no need to squeeze every last drop of productivity out of every free moment I have… 
Language learning can be a tricky hobby because the more time you put in, the more you tend to improve, which makes it tempting to put more and more in. But, a language like Japanese will take absolutely everything you give it and still always want more, so balance is important. 
Ok, thanks for reading my unscientific diary about me talking to myself!
I’ll watch this tomorrow.
I’ve actually just been shadowing what I’m already listening to and haven’t picked any specific speakers or type of content yet, but I am sure there could be benefits to it (I’ve heard of a language parent before, for example).