How big of a table have you played it with? The book says 3-5 (incl GM) is best; can it stretch to 6? What would you consider if doing so?

tabletops, bleeps/bloops, & other ephemeral interests.
How big of a table have you played it with? The book says 3-5 (incl GM) is best; can it stretch to 6? What would you consider if doing so?