You may need a lot more than 30 battles to reach the top of the GoodCommander trait.

The triggers for the GoodCommander trait is what you need to look at. They're further down the file. If you win a battle under certain conditions, you have x amount of chance to gain 1 point in the GoodCommander trait. But in some instances you can win many battles under the right conditions and not gain 1 bleedin' point!

In the 1.6 patch, CA made it a bit easier to gain the trait in BI, where it was much harder to gain than in RTW. Anyway, regardless of whether you're playing RTW or BI, to typically to stand a chance of gaining the good commander traits, you must clearly win a battle where the odds were more or less even before the battle started. Often you need to leave a few units behind before a battle starts so the odds are less favourable. If the odds are 4:1 in your favour for example, there's very little if any chance to gain another star. 2:1 in your favour is ok some of the time.