So as far as shading versus fading and the ratios go, the ratios can be used for both styles. The smaller the ratio, the quicker the change, the higher the ratio, the more subtle and slower the change. The most common shade ratios are the 3:1 and the 4:1 ratios.
When fading you are transitioning from one color into a contrasting color, and when shading you are moving from a light to dark of the same color.
I hope this cleared up some of the the questions you may have had about how shading charts work, how to do the math to get them to fit into your wraps, and also what the difference between shading or fading was. I write all my patterns down so it’s easier for me to keep track of the shading during a wrap, if you haven’t been writing them down and want to try it, I highly suggest it so you don’t have to count threads. If you have any questions, please feel free to ask!