There is orthogonal drawing with your front, side/s and back view of your object. Isometric and oblique for your overall view of the object. And explode to see how you project are connected together...
1. Original art work 2. stress relief 3. can be done at all place any time (un like tablet drawing or painting) 3.great practice for your all all drawing building hand eye coordination, learning...
The techniques of a freehand drawing is : 1.feels like a comfortable and being to mind a successful. 2.gather some information about the entire kinds of freehand drawing.
Yes, you can't be a mangaka if you do not know how to draw freehand. This is because when making the story board you need to draw the rough and then the other details that involve making the manga....