gamerprinter
Mapper/Publisher
If I went by that standard I'd sail the regular game about 1 week in 6; with 5 players plus me there's always someone doing something. Quorum is half the players, in this case 3 of 5.
Lanefan
It depends on your group, mine are more consistent - most of the players are 'unemployed' and almost never miss a session, one player misses 1 in 8 sessions, so it's never been a big problem for us.