There's no obvious exit to some of these and there's no paths that point towards towards the exit in some of these areas. Others you just walk in circles without realizing it because there's no ambient occlusion or underground map. It's hard to know how to get out of, say, point C on Frugis.
I can't be the only one. My entire squad spawned on me and we were still walking for a solid 3 minutes to try and find the way out.