More than 4-5 people simply gets impractical, but that's not such a big deal. With some restrictions you can have meetings with more people and e.g. at a long t

More than 4-5 people simply gets impractical, but that's not such a big deal. With some restrictions you can have meetings with more people and e.g. at a long table it's simply a balance of distance (for voice and non verbal clues) and frustration of not being able to talk (at some point you just tell it your neighbor, splitting the group when it gets too big).