Probably tentpoles. If you have large tents, the pole is a great way to keep it from collapsing in on itself. They're pretty traditional as far as war camps go. You want to minimize the amount of tents you have to carry, so going with larger tents that can fit more people beats out having many smaller tents.
Depends on the time and place in history, though. These tents in the picture are from WW2. Mongols used yurts which had more structural integrity, but they also primarily lived out of yurts without any standing structures to go "home" to. Expeditionary forces and scouts would use smaller personal tents that they would keep rolled up in their packs, but they traveled in small groups so they didn't need a lot of supplies.
Over all, I'd say the tents are pretty realistic for the time period they're going for. If you're not looking out of a crenulated tower at oncoming enemies, that'd probably be where you slept most nights on campaign.