You don't need to toggle on/off every nested collection individually just hold shift when turning on the main one.
Awesome, I have done a complex scene specifically to exercise on it throughout this course. It's the best I can do but I see I've made some mistakes that I can see right away, (struggle with color correction, lighting, and apparently scene set-up) I would like to show you if you can comment on it. Also, I ran into a problem with the cryptomatte node when working with rendered images (OpenEXR M.). The mask ends up very pixelated compared to when I use cryptomatte with the with render layers node.