The Shading Handjob Correlation states that if one is good at shading with their graphite pencil, then they will give really pleasureable handjobs

When you eat dirt for the first time and leave your family to build a shack in the woods

If you are good at shading in drawings the you are good at giving handjobs.
so, good shaders=good handjob givers
particularly if you are female. If you're a really good shader, then you're really good at giving handjobs.