I have started taking design fundamental classes that focus on primitive shapes and it has really helped me quicker on line sketching and delivering a better visual form when sketching from imagination. However tedious it is, it also reminds me that it is a 50/50 % regimen. I should spend half my time on learning, tutorials and practice the fundamentals, while also devoting the other half of the time on personal art. Below is one practice, trying to learn how to render shades by marker better and trying to capture it through primitive shapes with lighting.