When I reviewed the pictures later it was interesting to note how the color of the light had changed as the sun began to set.
Yeah, that makes sense!
How would you keep up with all the different colors of light and do it quickly?
I think what you said at the end, “Manual WB takes a lot of practice to learn just like Manual exposure took a lot of practice to learn” is one answer. 🙂 Practice, practice, practice. And in the meantime, similar to using the semi-automatic modes like Aperture Priority or Shutter Priority when you’re still working on Manual, keep using auto WB or the other preset WB settings when you need to. Especially since you’re shooting in RAW.