Once a precedent has been established, it can be hard to change people's minds, especially if it was fast/easy/convenient the first time around. It really depends on the group.

I think it works well in the writer's case. He knows his audience and has probably worked with them long enough to know where they like to go to eat. He's not taking the risk of McDonald's every day. There wasn't a chance that would happen anyway because even if one or two person wanted to go to McDonalds two days in a row, the group would win out and override it.