I understand your problems with this but I think you are discounting what this means for the Seanchan. You have arguably the most highly trained military force and you can now move and lighting speed in comparison to MOST of you enemies.

Another thing, I never suggested putting 100000 people in one place, I suggested putting a 1000 people in one place. If those bands move simultaneously (which due to the organization I think the Seanchan could mange fairly easy) you could move 100000 men to an area then march the remaining way to your target, plus those bands don’t have to be in the same starting place to move as one. Additionally, you could move half your force behind your enemy in the night and crush them while they slept. Like you said, even if there are multiple exits at a stadium it takes hours to move those people out, I am suggesting the same sort of idea only in a much more structured and efficient manner then what occurs after a major sporting event.

I agree that they are limited because they cannot link, but the Seanchan have shown they are a resourceful bunch and I think could make this "limited" form of Gateways just as efficient as the linked kind. As far as it being implemented though, I don’t think Rand’s or any other force in the world could use it as efficiently. I just think there would be to many "cooks in the kitchen" and such when it comes to organising something like a huge Gateway. That is not to say it can’t/won’t be done; I just think the Seanchan are more “one-minded” without the level of infighting that everyone seems to experience thus allowing them to implement something like this in an effective way.

Finally I should say I don’t think the Seanchan should use Gateways in this manner and go directly into battle, which would be a slaughter. They could however fairly stealthily and very quickly move large forces around the world, much like the SAS did just with a much larger number of Gateways, and appear outside a city before anyone knows they are there.

EDIT: If the Seanchan get Gateways we can assume they can learn to tie off flows from the same source.