I believe the point of painting is not to paint like someone else, but for each painter to find their own voice and tell their own story. That said, I also believe in Degas, who said, "Art is not what you see, but what you make others see!"
Thus, those who know me and my work know I am not a realist painter. I prefer to approach my work from a very personal and expressive point of view, in which color and light play strong roles.
When it comes to light, shade and shadows I see these as very strong and expressive tools in a painter's kit, which should be used with expression and confidence. That said, there are specific and definite principles which are important to understand about light, shade and shadow, and that's how I paint and teach on the subject.
Using simple children's block shapes when teaching about light, shade and shadow is a simplified visual approach which helps to illustrate some of these important principles. The illustrations are not meant to be "paintings", per se, rather they are simply illustrations of the key learning points.
Here's another example from my tutorial illustrating how shade and shadows are darker values and cooler temperature of the surfaces on which they fall:
It's up to every painter to interpret for themselves when and how they will use and interpret these key principles. Or not!