Psychological warfare seems more relevant to me in big foggy games.
Here's a nice example from an 8-player game I won a while back:
- Click image to enlarge.
While many of my borders are easily broken,
my opponents could not tell how many troops I had hidden behind the lines to counter with. And 2s on borders don't pose such a threat. However, some stacks (such as the 250 on Krasnoyarsk) can be used to intimidate...to assure the enemies that I do have lots of troops. I have 2s on every region because they're bloody difficult to get rid of, and - being unlimited in reinforcements - could make a big stack if needed.