This always bugged me in Arma 2 as well. I'd give the AI a formation and they would stick to it no matter what the cost. This would result in them taking any path, however elaborate or dangerous, just so they could be in the exact spot they're supposed to be in. It makes stealth difficult when you want to creep along a wall with enemies on the other side and one or more of your team mates runs right around it onto the other side, getting killed in the process.
I quickly recorded a video during a mission I was putting together in the editor to show off this behaviour.
youtube.com/watch?v=wwSXatXM7gQ
[Removed the start of the link because it wouldn't let me post it]