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.

I don't understand fully your problem but I think lesson 5 information about head construction could be helpful. From what I understand of what you are saying, the only variety you need to change the angle of the head is to change the point where both lines cross. If you have a circle and both lines cross in the middle, the face is drawn from the front and if you move the crossing point to a side, you are drawing it sideways. If you move the crossing point in a direction the "viewer" moves in the opposite. If the crossing happens on the bottom of the circle, the viewer is on top on what is viewing.

I hope it helps.

Just to add to the other advice, the truth is it is hard to do especially if you are not used to it. You have to experiment, try things, get things wrong. However after a period of time things start to connect and you start finding it a bit more intuitive. It is this hard work that reshapes your brain until you wonder what you found so difficult.

It's also the reason for the 50% rule. You have to do your own work and not just follow others for the learning to have value and for you to become your own artist.

Maybe you could start off by adding the lines over a photograph, could be at the computer or in a newspaper/magazine idk whatever fits you best and then try to recreate the lines on paper, to check if you understood where the lines should go. Sometimes i do this when i'm having a hard time finding the angles.

I did those on paint https://imgur.com/a/P03KXqE

The Loomis method can be kind of confusing at first, it's kinda tricky on extreme angles, it took me some while to get used to it, but once you do becomes very intuitive. The most important thing is to understand where you should be looking for the angles, Proko explains this in his videos.

There's a Steve Houston video in which he explains how to construct the head, i don't think he mentions the Loomis method, but it's basically what he's talking about, and he also explains how this was applied in some artworks. His approach is very constructive and didactic.

https://www.youtube.com/watch?v=2T7cDY7YDsg&pp=ugMICgJwdBABGAE%3D

If you already saw this then nevermind lmao.

Anyways, hope this helps!

I second checking out Fun with a Pencil, which is what I dipped into when wanting to learn how to draw the head in 2012. From memory, you draw a bunch of blobs and put features on them to start off with before moving on to the sphere. I couldn't draw circles very well at the time, so I simple traced a coin 20 times and then experimented with different ellipse configurations.

Another thing to try is to get a styrofoam ball (craft stores should have them), draw the verticle and horizonal lines in marker, and poke toothpicks through for the poles. You can then use this as an observational model to practise changing the angles, recording the different configurations of the ellipses, and move on to making up your own configurations.

Everyone has had great suggestions, but I didn't see anyone mention looking at it as form. When you said that you can copy a face and shade it well, how do you think you can do that? Do you shade things a certain way because you understand the shape and light source correctly, or because you can just see in the photo that it is darker and lighter? I am only asking because the loomis method is just creating the head as a basic shape and adding features. Can you draw a rectangular box in different angles from imagination? I think that is all it really is. The loomis head is just a sphere with the sides chopped off. If you can draw that from different angles, adding the chin shouldn't be too hard. One thing that helped me was to actually get a skull (I 3D printed one) and drew it from different angles. I would position the skull, draw a loomis head and then add the details of the eyes, nose and mouth. The loomis method is essentially creating a skull in simple form.