My wife prefers one on one. We have twice attended a cuckold/hotwife club which meets every three months at a private home and furnishes selected guys for parties with the wives. Husbands are allowed to watch but not participate. Each wife and each bull are assigned numbers upon arrival and after a preliminary business-like meeting, the matching numbers are paired off for the night to a bedroom or other available room if all bedrooms are occupied. When more wives show up than guys, two wives can participate with the same man.
But my wife has said she doesn't care for multiple guys at one time.