I've participated in these through Unreasonable (whose guide is linked at the bottom). They didn't use a single table, but rather broke folks down into tables of 6 or 8. Each table ended up having very different conversations, but in general they ended up being meaningful. Some people would share extremely personal details about their lives/relationships/etc. It was a good way to get to know our cohort very well in a short period of time. It also didn't hurt that Unreasonable always served very, very good food!