It teaches 3 critical drawing things 1) think in terms of lines.
2) every line is in relation to something (sometimes just the frame). An example of (2) would be, in the face, there is lot of relation between horizontal and vertical (relation to the frame) and for example, the eyes are in relation which each other via an expression, so you better draw them together, with one stroke to start with. Thats the point of relations: draw them at once or one after the other.
And 3) notice the diagonals and horizontal/vertical in your drawing.
It teaches 3 critical drawing things 1) think in terms of lines.
2) every line is in relation to something (sometimes just the frame). An example of (2) would be, in the face, there is lot of relation between horizontal and vertical (relation to the frame) and for example, the eyes are in relation which each other via an expression, so you better draw them together, with one stroke to start with. Thats the point of relations: draw them at once or one after the other.
And 3) notice the diagonals and horizontal/vertical in your drawing.