In an echelon logistics structure, the flow of products typically proceeds through a series of established arrangements or stages, from the origin to the final destination. This structure involves multiple layers, such as manufacturers, wholesalers, distributors, and retailers, each adding value and passing the product along the chain. This contrasts with direct logistics structures, where products move directly from the producer to the consumer without intermediaries, and combined or indirect structures, which involve a mix of direct and echelon methods.References: APICS Dictionary; APICS CPIM Exam Content Manual.

Order fulfillment lead times are a critical metric for measuring supply chain responsiveness. This metric reflects the total time taken from receiving an order to delivering the product to the customer. Shorter lead times indicate a more responsive supply chain that can quickly adapt to changes in demand and deliver products faster. It encompasses various stages of the supply chain, including order processing, manufacturing, and logistics, providing a comprehensive measure of how swiftly the supply chain can respond to customer needs. Percentage of orders delivered on time, retail inventory days of supply, and upside production flexibility are important metrics but do not capture the overall responsiveness of the supply chain as effectively as order fulfillment lead times.
References:
* Chopra, S., & Meindl, P. (2016). Supply Chain Management: Strategy, Planning, and Operation.
Pearson.
* Harrison, A., & Van Hoek, R. (2011). Logistics Management and Strategy: Competing through the Supply Chain. Pearson.