Most supply chains are driven by orders, someone reacts when an order is received.
The niggling question is always about demand, as most recognise it drives orders, inventories, innovation, competitive pressure, and so on, but is rarely measured.
Orders are at the end of the process, they arrive after making allowances for out of stocks, poor display, customers memory, competitive activity, the skill and interest of the sales person, and many other factors.
Demand is created by understanding the customer, and positioning your good or services in their minds as the best value solution available to address their need. This is longer term stuff, harder to measure, easy to ignore, but it is the foundation of commercial sustainability.
How much better would it be to have in place signals that reflect demand, they might give us an opportunity to reduce the incidence of lost opportunities, whilst better managing our investment in inventories, brands, customers, and the short term sales tactics used to stimulate an order.