We have one annually for my company. It's at a casino, with a few scheduled meals and some activities (video game room, trivia done by a professional company).

It's voluntary and employees are allowed to bring their spouse. I think it helps a lot with communication, especially since we are a distributed team and most peoplr don't see each other.

But it's hard for me to know for sure, no one tells the owners the truth. It is voluntary and almost everyone attends. I think most people think of it as a free vacation.