New math, Nate?
Nope.
You and first partner, your share is 50%. Your personal cost dropped by 50% to own a plane.
You and two partners, your share is now 33.33%. Rounded to 33, your personal cost dropped only 12% to add this partner.
You and three partners, your share is now 25%, and your costs dropped another 12% rounded.
(Put the decimals back in if you like, it doesn't matter for purposes of this point.)
You and four partners, your share is now 20%. Your costs only dropped 5% to add this partner.
The post was to show that there's a significant diminishing return on adding new partners beyond 3 or 4. At five people, the delta in your price is only 5% when you add person number five.
But your chances of scheduling the aircraft when you want it are dropping like a rock at five. More people, more chances for interpersonal peoblems, very little fiscal gain for the original four. Or three or two.
The biggest bang for the buck is adding that first partner. Price cut literally in half.
After that, it's a marginal change until partner number five, at which point it's probably not worth the potential problems of adding another human being to the mix. A 5% discount for the originally four isn't very compelling.
We specifically wrote into the LLC by-laws that no further patters beyond a fifth could join the LLC unless an additional aircraft is added, for the above reason. We decided we could live with 5 because there's always someone who isn't flying enough at any particular time.
A non-flyer saving everyone else 5% is maybe reasonable. If all five are flying heavily, you might as well go rent from the FBO that has 20 aircraft 100 yards from our hangar.