If Scouts don't linger and move swiftly they can accomplish a lot. Planning is a key. There should not be an expectation that a Scout can do everything at a Jambo. It's like going to Disneyland. Troop leaders can, however, observe their Scouts and cheer them on.
Adults assigned to troops often show encouragement, take pictures, videos, and hold gear.
Make sure the scouts have their water. Consider the buddy system for boys with the same interests. They may all be in the Action Center but want to do different activities. One list member says that he thinks of the adult activity at the Jamboree as similar to going to summer camp. The program is rich and available for the scouts.