Always fancied being the subject of a well organised gangbang, however experience thus far re the organisation is that if it's a group of men sourced vis putting up an advert for gb and who wants to attend (male wise) then it's pretty much doomed to failure and for the very reasons you seem to have experienced recently.
Personally speaking, a gb needs to be when an organised group of males that form part of a gb group and where a 'pool' can sort of be picked from them for the gb...then that seems to work. I've seen what looks like a couple of well organised gb groups of males, all known to each other, all part of the group and when an opportunity arises they seem to be able to do the deed and everyone is happy....hastily arranged gb's with males not really known to each other and who have simply stated an interest in attending one....well it's a recipe for disaster.