The formula for dividing up tickets between airlines is a trade secret, very complex and highly unfair. The RTW products are extremely stilted. The 3 "ocean" sectors (trans-Atlantic, trans-Pacific and trans-Asia) get the lion's share of the revenue (maybe 20% each, or 60% total), while the remaining sectors divide the remaining ticket value (so the 17 sectors would get <3% of the ticket price each, while the trans-Atlantic sector gets 20% or 7 times as much).
I would imagine this is true only if someone actually used all 20 segments. If someone on a *ONE3 flew only 5 or 6 total segments, then isn't it almost certain that the revenue for the three non-intercontinental flights gets divvied up entirely between those 2 or 3 segments? In many cases, this could be a large amount of revenue, even if the intercontinental segments get 60% of the revenue. I doubt that the issuing carrier just gets to keep extra money because not all 20 segments are used.
