Our office website's forum is pretty small so just 1 admin and 1 moderator can handle it for now. When I was in a forum of horse racing aficionadoes, there were so many moderators - 1 for each board and sometimes even 2, that's aside from the so called global moderators that has the entire forum for their territory. There's also the admin and assistant admin (2 persons). Those "officers" of the forum were appointed just for the position, more on their dynamism and frequency of logging in. But I don't see a need for such many moderators.