I've seen that happen with FF and KH shoots, which is why I don't go to them. It becomes an odd mash...
The Square's big enough that the giant shoot could split in two actually, or three, so people from different games can gather or get pics... I'm not sure on who everyone's all cosplaying so I almost think a general shoot would be simpler then having say, 3 or so for Abyss, Symphonia and then a third for all else.
I think it kind of depends too on how the attendees of the shoots work together vocally organizing going say Phantasia first, Symphonia second, and devote say 10 min to each? That said, we could work out a time of say an hour or so for the whole Tales Of crew but have it inside of itself as a list of who goes first for 10-15 or 20 minutes, depending on the size of the group.
Example:
Tales Of Shoot @ Pioneer Square 5pm
Phantasia 5, Abyss 5:20, Symphonia 5:40, Other 6.
Then have it last until say 6:20 and have maybe anyone who arrives late to get pictures during the other and after time...?