Having played lots of churches I think Ultraman really doesnt get it.
Many churches in the US are using 5 or more piece bands in rooms designed to be auditoriums or general purpose rooms, or rented gymnasiums.
Drums, Guitar(s), Bass, Keys, Woodwinds, etc... On top of at least 2 vocal mixes.(worship leader and background singers)
Im not hear to debate the mega church, I do that elsewhere, but the simple fact is they are trying put a quality effort into thier music.
Most of the performers and soundmen are amateurs with little to no profesional experience especially outside the church.
To the original question:
Do you need 7 monitors or 7 monitor mixes.
If you need 7 mixes why? Can't people just get along?
Can you cut back on your mixing needs with a better stage layout and controling stage volume. (not just turning people up or down but better aiming amps at the drummer, guitarist, bass player etc...)
You can daisy chain additional monitors into sub groups to make it work. Most of the solutions I have seen that allow 7 monitor mixes would be more money than most boards, or require a second board. The reality is most church soundguys(and clubs) wouldnt know how to mix it. I wouldnt want to if i thought i could.
Here's how I would work it as the sound guy with four monitor mixes.
Instruments - Guitar, Bass, Drums, etc... Using stage volume and a well laid out stage this group should be pretty easy to satisfy. They usually just want instruments and lead vocal. Unless my guitar is runing direct or my amp is miked off stage no one including me usually wants me in the monitors.
Leader- They usually want it all, with themselves boosted. If they also play an instrument this complicates things.
Back ground vocals- This may take 2 mixes depending on the number and type of people. They usually want lead vocal, themselves and very little of the instruments.
I know this is 3 of 4 mixes. If i can i would then use the 4th for seperating a group if I needed to. Or ignore it and make life 25% easier as the sound guy. Also I might regroup if keys are in the mix.
Depending on the room and amps/people involved I often wouldnt put any instruments in the monitors unless we have winds or keys or something weird.
My $.02