You might want to add the fact that if you're set to unlimited for fortifications, you can fortify a country that's adjacent to a country that you own, that's adjacent to the country which has your extra armies in it.
Example: Say you own each territory in Asia and all of North America, and you have 50 armies on the Middle East. You could fortify Central America with your armies from the Middle East, even though they're not directly next to each other, since you own all the territories in between.
It's easier and faster than transferring the armies from the Middle East to India to China to Mongolia to Japan to Kamchatka to Alaska to Alberta to Western United States to Central America, at any rate.
