Each campaign book is a bit different. The early ones throw scenarios at you to pick and choose. Some campaign books present more balanced fights, while others tend to be a bit more historical you get what you get and good luck!.
Some later ones go for more a linked series feel, giving a very nice feel of events of the time. The very best one, in my opinion, is Stalingrad as you are fighting multiple battles over many sectors of a map whose changing ownership has consequences, so it really is an ongoing and organic campaign.
As Nat said earlier, BA is more open ended that some other games whose ‘officialness’ dominates (looking at you Wizards of the Coast, and Games Workshop). If you go in for tournaments, I guess they would care more about such things, but even they commonly often use their own house rules and so on. I come form both open and closed types of rules and I know it can feel a bit “Can we do this? Can we have Russian fighting Russians in the jungle?” yes, if you want.
