As I said before, supplies aren't needed, or in the amount we typically think are needed because Damane would be able to hook up with supply camps. Soldiers could carry a week’s worth of rations and the basics themselves.

Plus, why not a man every 3 seconds? If they are marching in a straight line you could easily move that number of people (100000-200000) in under 3 hours. I don’t know how in the world it could take 30 seconds a man. Even still though, at 30 seconds a man you could move an army of 100000 troops in under 10 hours, that is still huge. Though at that pace the Damane would tire. However, holding a Gateway for an hour wouldn't be so bad, plus they could be tied off making it even easier.

Finally Grady and Neald got so tired because they didn't tie Gateways off very often, if ever.