When I worked as Supply Chain Director in Procter & Gamble, every year we completed a loss analysis. To do that, we picked a specific skin-care product and leveraged a tool called value-stream-mapping to map out the whole supply chain for each of the components and ingredients on a large white-board. The captured flow could lead back more than 12 months, when some of the raw materials were prefabricated.
Then, we looked at all the steps in the supply chain which actually generated value. For example, when we mixed the ingredients, filled the jar, put a label on, and added a cap to close the jar. You can imagine the actual value-creation-time was only a few minutes, whereas there were weeks and months lost in waiting, transportation, as well as other non-value-added movements.