Yes, I understand why canonical proportions of the face and body are needed. This is especially important for me in sculpture. I always first did the marking on the wooden billet in accordance with the proportions.
However, as I cut out, someone began to guide my hands ...
While maintaining the overall proportions, sometimes unexpected faces and figures turned out :))

But you're right, you always need a starting point and a point of comparison. Thank you for this lesson.