What did you enjoy doing at age 10?

Perfection is boring, and drawings of children are demanding.

children drawing proportions

Jean Cousin, "L'art de dessiner," circa 1768

Head to belly button proportion is for drawing children, why do you find this odd?

Drawing the children form

As a rule-of-thumb, a good way to deal with human proportions is to ignore the rules.

Jean Cousin, Author of seventeenth century drawing tutorial