Loomis' previous book, Fun with a pencil, seems to be what you're looking for. ( https://archive.org/details/andrew-loomis-fun-with-a-pencil )

It goes in more detail in how to approach head construction, including the "draw this from a bunch of angles" phase. I like the approach of that book better than Head and Hands (or even Figure Drawing for All it's Worth), it goes from cartoon to realistic in small steps so you're less likely to be overwhelmed and is full of step-by-step examples. It's explanation for the "bunch of angles" phase is quite short, but it's all there is to it: The core skill to master for the whole process to work is the sphere, I mean, drawing a sphere with belivable longitude and latitude lines. So you could take the 250 box challenge and apply it to spheres. Once you know how to draw an equator on a sphere you can align features to it and the whole thing becomes much easier.