They're all there for the same reason. Once party perimeters are established, the pressure's off for the recon teams. They can start drinking. Then, the next shift must swing into action. Huge smokers on trailers have to be delivered.
Tents have to be erected.
Porta Potties have to be dropped off. Kegs and margarita machines have to be set up, and ice deliveries need to be made. Furniture, ranging from card tables and folding chairs to three-piece sectional couches and Barcaloungers, has to be wrestled into place, and rugs laid out. Some groups perform all of these tasks the night before so they can concentrate on partying all night, keeping crew members there around the clock in shifts. Others, usually the old salts, mobilize very early on Saturday morning, and shuttle everything to the site in pickups.