tl;dr: Elevator scheduling evolved from the simple SCAN/LOOK algorithms to Otis' RSR, which scores cars based on ETA, load, direction-matching, and anti-bunching, then re-optimizes every 5 seconds. Benchmarks show RSR beats LOOK at moderate traffic, but LOOK wins at high flow rates or in small buildings. Counterintuitively, Destination Dispatch kiosks usually perform worse than traditional up/down buttons because locking passengers to a specific car eliminates the flexibility that periodic re-optimization provides.