If I'm going to war often and expanding, Battlefield Commissions is a must, especially early on since there are less good CBs and thus more BB to burn off, meaning more time between wars. Plus, it's much more difficult to keep Army tradition high than cultural tradition. You get Last Jousting Tournament, but it costs a lot more than you want to pay early game. There's the Military Academy building later on, but that's at Land Tech 30. And I guess you can get an advisor to help out, but that takes up a precious slot. Given that generals can be so decisive during war and I always try to have at least two high-level ones hanging around, Battlefield Commissions is a lifesaver.
Playing MEIOU now which nerfed it, which makes me miss it even more.