I think those light videos can work as an introduction, but then you have to start to dig in. Watch something for 20 minutes and make notes. Then study 2 hours with 1 to 2 breaks. I can't keep studying more than 2 hours a day because it's exhausting, but I may do a 30-minute refresh and recap later in the same day.
also i can rarely allocate 4 hrs of time to anything with two young kids at home
What worked for me was building a system that lets me think consistently everyday. And by system, I mean sitting in a library with paper books and if really necessary, with my existing laptop.
also the new ui that is more visual is making a huge difference. only think i dont like is that i take a lot of detours but chat is linear instead of a tree.