What is the crucial step on supply chain, Selection, procurement, distribution or use ? and Why ?

Crucial cases are when launching new products. We are planning the supply chain procedure from the very beginning. As we go on the actual process we found out there is some procedure not applicable for the new products. again we need to adjust the procedure. there always changes, As a supply chain professional we should be open minded and flexible to our thinking so that we can easily adapt the situation and come up with the right decision at the right time.