One of our company's expertise is photo studio management and equipment. Also, from the client's side, efficient execution. I spent eight years, traveling the globe on photo shoots for consumer product campaigns. I had strict protocol on-set/location, defined roles and responsibilities and restricted personnel.
It amazes me, the number of people clients allow to attend shoots. Especially, considering 2/3 of them just spend time on their Blackberrys or iPhones, without regard to the task at hand. Yes, there is a lot of downtime and these tools can help productivity. Just peer over the shoulder of one or two people and it's not their work on the screen, but FaceBook and Twitter. Now define productivity.
Professional photography is very expensive and time dependent. My advice is to define accountability for each member of the client's team attending the shoot. Convey these roles to the studio/agency team. Reducing the number of people on-set with reduce your costs. I guarantee it! Right off the bat, fewer people traveling and less people to feed by the craft service. Oh, you thought lunch was free? "There's no such thing as a free lunch." It's all part of the day rate, if not broken out on the quote.
How many people does it take to accomplish a shot? Just one less.