Traditional Chinese measures are relative and not absolute (i.e., a chuen (cun or Chinese “inch”) will be smaller on a smaller person than a larger person, where a western metric unit like centimeter will be the same for both, regardless of their individual size).

In my experience, if you learn from any non-Westernized Chinese sifu, they will give you measures in this way (if TCM is shared knowledge, then with accupoints, if not then with landmarks — i.e., one tiger’s mouth (thumb-to-index span of grip-shaped hand) straight out from the nose).

Since paths require structure, describing the measures for beginning through end point commonly makes them easier to learn, retain, and refer back to.

This is why Siu Lien Tao, in most systems, open the posture by swiveling the toes out and then the heels rather than just placing the feet 24 inches / 60 cm apart (for example). Since everyone’s foot length is different, the width attained through this method will be also be different and tailored to the individual.

Likewise, this is why the “correct” measurements for a wooden dummy are never provided in inches or centimeters, but references that match the intended user (i.e. the upper arms are the hight of your own arm in the Tan Sao position).