The early bird tickets seem to always be purchased by the same people. These are the ‘lifers’ who always attend our events. Does not seem to be a sales advantage but does give a discount to this loyal crowd.
Admittedly, have not analyzed this data but see familiar names when reviewing registrants. Some confirmation bias is likely at play.
One time we tried limiting the ticket capacity for the early tier but there were howls of protest from those who missed out. Looking back on it we realized that arrangement is biased against older folks who tend to check their email less frequently.
Since email responses have a short response window, we throttle ticket sales with email campaigns. After 30-hours nobody clicks through to purchase. Timing campaigns seems to control how many of each tier are sold.
Discounts + campaigns seem to be the effective tool to influence last-minute purchase behavior.