Any large gathering needs attendants, or ushers. Here's some links on how the Billy Graham crusade is run for comparison. I've noticed that the WTBTS does not have an 'altar call', no volunteer counsellors, or follow up to the appeal. At a WTS convention, people listen, clap, pick up their literature, and go home. I think the Billy Graham crusades do give a satisfying sense of purpose to the participating churches as trained volunteers have an opportunity to follow up with new converts.
http://www.wheaton.edu/bgc/archives/docs/haytxt.html
Q & A from the Billy Graham Crusade site:
Q. How do churches share in a crusade? A. In some cases, through the addition of new members, but apart from this numerical benefit, they share through the participation of their members in ways such as:- Counselors who are trained and motivated to help inquirers at the meetings and as they gain experience in spiritual counseling and leading small group Bible Studies.
- Choir members who rehearse and sing music which prepares the hearts of those in attendance to respond to the Gospel.
- Ushers who greet, distribute programs, collect an offering and serve as needed.
These and other opportunities for participation have made the rekindling of spiritual fervor in the hearts of church members one of the major accomplishments of the crusades. The backbone of a successful crusade is the gift of the evangelist joined with the gifts of local pastors and their people.
http://www.billygraham.org/mediaRelations/crusadeFAQ.asp
Usher application form: