I only ever did it once and it was as part of a gathering for people who are into polyamory - called polyday - so probably not typical. anyway, it was fun. we all sat in two long lines and the folk in the line opposite me moved along every three minutes, so i just sat there smiling and felt a bit like i was a host and they were visiting me... i actually said very little, just smiled a lot and listened. i think everyone was so nervous that they felt they had to fill the time, i would ask one question, such as "have you had a good day so far?" or "so what are you into/doing with your life/hoping for?" and my work would be done, they would chat away and then the bell would ring.
it was successful for me in the sense that afterwards i was approached by someone who is now one of my lovers, and that is how we met.