Next-Best-Action in Pega Customer Decision Hub is applied to scenarios involving decision-making about the best course of action in real-time. This typically applies to personalized customer interactions, such as determining if a borrower gets a loan, where the system evaluates various factors to decide the most appropriate action. Options like optimizing supply chain management, predicting machine failure, and optimizing inventories are more related to operational or predictive analytics, not personalized next-best actions for customer decisions.