Tommy,
I have seen systems of:
3 - (front-middle-back) although I think courses are forced into that more than want it
5 - (center and four corners) mostly at private clubs
6 - (front-middle-back on bot left and right) This works okay, except when a club is closed on Monday, where it tends to put the pin back in the same place every day for subsequent weeks. Maybe that is why Gil wanted 7, and would be interested to see if he had a generalized diagram, maybe a combo of a middle pin and the 6 pin system? Or maybe, he designs the green and lets the super figure it out.
9 - a true tic-tac-toe board for very busy public courses with very large greens.
In general, a "pin position" is an 8-10 foot diameter circle under 3% slope, maybe under 2.25% slope for others.
In general, cup locations take from 14-21 days to heal properly, with low play high budget clubs trending lower and high play low budget courses trending higher. I suspect that even in a 6-7 day rotation, each of those would require at least 2 adjacent pin positions, or an area 8-10 by 16-20 feet.