When you have one guy who makes a 7 million strong army, the rest of the players suddenly think that their army is too small and beef it up to 8 million. It's a vicious circle if not sorted out by the GM. I generally advocate the 10% rule we have in Precipice - you can only have 10% of your population maximum in the army and that's only if you're in the middle of a national emergency. For the most part, your army should barely scrape 2% of total population. It all seems very number crunchy, I know but that's not my usual style. I tend to look at the size of most modern armies (200,000 or under seems to be the norm in most European countries), consider whatever political factors there are and then put a low number. The NRP's I'm in tend to be more about the characters within the nation than faceless politicians and tanks anyway. 

A few I've joined in the Nation section are just full of people who undo their zipper in their CS and start waving their dick about, which isn't something I'd advocate.