To keep track of the wait times, "FLIK" cards were used. They were red cards on lanyards that had text written on them in spanish and english, stating "This card helps Cast Members determine the most accurate wait time. Please hand this to the Cast Member as you board the attraction." The CM would scan the card at the end of the line, hand it to a guest, then a CM would scan at the load area, and it would update the wait time. This technology has since been replaced with long range RFID readers scanning a magic band and scanning the same band again at the load area, thus eliminating the need for the cards. The wait time can be manually adjusted by a CM if needed, but if left alone, it would just read magic bands all day long.
Reasons for CM override would be during a downtime, or if the queue extends past the Greeter position (which it does now with social distancing) because the line entrance is where the scanner is located.