The best efficiency advice i can give:
Split your runs, do two areas at the same time. Every time you get 10 or more people (even 9 if you can handle it, but this may need some practice), simply split. Plan farming runs with groups making 6 - 4.
What you accomplish with this is basicly targetting more NMs on the same time. The downside is that you will need a rather varied job pool, but i seen from your members that you could pull it off. Ofcourse, this means more logistical problems as you will need to allocate people in the right parties so they get the chance to the right drops.
For the 6 man party: A 6 man party can do any zone and any boss without exception. Some bosses might be hard at first with just 6, but it's possible. Some others are simply equaly easy. Among the easy ones with 6 you get Battleclad and Armored. Harder may be Long-Bowed and Long-Armed, so you may want to plan full group runs for these two bosses and splits when you do the other two at first.
For the 4 man party: You can farm any area for all targets conceivable with 4 people. For example, Silver Sea is possible to target Hammer -> Powder -> GG3 or Hammer -> Dekka -> GG1 or doing some changes get to GG3, etc. Arrapago is the same deal, all targets minus 6F QQTHs, Bhaf you can farm 2 full doors without much problem or 3 doors if you exit early (unlikely to do 4F door

) and ZR may prove a bit harder, needing 5 people.
The bottom line simply is that by spliting a big group in two you are targetting more NMs than you normaly would if you cramp 10 people in one zone and can still retain your chances of doing boss fights. This is specialy true if your drops are pre allocated by your loot system. That is, maybe some people will simply win over a piece that drops due to their points or whatever rule you use, so the excess people in the area don't really have a chance to lot on such piece, making their presence rather useless in the end, when you could be doing the same with less people.
Split.
