2 posts below the link Rob outlines his approach for back width and thickness. This is what I have started incorporating into my split as well. You can see in his pictures the massive short term progress he made with this method.
As for shoulders I think I’m a bit of an oddball. Raises don’t do a ton for me. I mix them in here and there because I keep thinking they are the missing piece, but pressing is the only thing that really smashed my delts. Steep incline pressing, arnold presses and BB OHP (BBB style) are my shoulder builders. I do a boatload of facepulls, and mix in some rear delt flyes as well. Again, my shoulders might not be a strength of mine, but lat or front raises don’t seem to be the answer for me.