Richard P. answered 06/11/19
Pencil and Charcoal portraiture tutor
The main factor for me has always been either time and texture. Every mark you lay down will affect the drawing, in fact it will effect how your drawing "feels". What I mean is that while you could use dots to shade hair, it would take much more time and the texture of it would most likely not look like hair. The amount of time it would take to do so would be much longer than with just using straight lines and blending. Play around of course, perhaps you may find a certain technique adds something you find useful in making art!