Abstract: Numbers of servers at latter stage services are synchronized with arrivals of customers at the latter stage services. Detecting entering customers' entries and passages by intermediate points are communicated to a computer. The computer predicts arrivals of customers for the latter stage services and needs for increases or decreases in numbers of servers. Lead times allow changing numbers of servers at the latter stage services to meet changing needs. Detections of times of servers with customers and detections of arrivals of customers at the latter stage services are communicated to the computer aid the estimations of changed requirements for numbers of servers. The computer provides the estimations of server requirement changes to managers and automated controllers with sufficient lead time to facilitate smooth transitions in increasing or decreasing the numbers of servers. Wait lines at checkout registers, call center on-hold times and inter-computer communication delays are avoided.