I tried some free courses on YouTube and I could learn a bit, but often got confused with the speed and complexity presented on a “Beginner's level course” or found it way too slow and simple.
What I like the most about Zach's courses is that he makes the learning process engaging, interesting and fun. You always have a nice looking 3D scene to learn about the topics he is teaching. Zach created a storytelling way of teaching combined with a cool project to immediately exercise what you learn in a very comfortable pace, that makes learning 3D an addicted and fun adventure, despite its complexity and big volume of subjects to master.
The only aspect I think Zach could improve in his course are his jokes. He has great ideas for jokes, and some jokes are super funny, but sometimes his timing and execution needs a bit of more references, I think.
His knowledge and techniques are the best I've seen so far for learning 3D. I look forward to more of his courses, for sure.