Set the delivery promise your storefront advertises, then balance the conversion it wins against the on-time performance and cost it demands. Miss the promise and pay penalties.
The delivery promise you advertise (same-day, next-day, 2-day) lifts conversion but demands a matching on-time performance; missing it costs penalties and NPS.
On-time performance builds from buffer, carrier mix, staffing and inventory, minus promise tightness and traffic. Bolder promises need higher reliability.
Set the promise just inside the reliability you can actually deliver; the best margin is where conversion gain still beats penalty risk.
