Yes, six seems to be our favorite number in terms of character juggling, whether they're all in the same unit or not (not including side characters, for example, in the Lust and Chastity series we have a set of four and a pair of two as 'main characters'). Except, of course, in Cuddlefish. One pair's more opportunistic, but it's pretty much just 2 pairs of main characters. I went off on a tangent there. Everything we piece together in world-building is fairly even, @Rambling Robin's ideas and mine.