First of all, it was you who said the 4 artillery divisions is cost-effective. I merely refuted that, because it is quite hard to say what is cost-effective. Now all of the sudden you want me to tell what your "cost-effective" means?
I guess it's just a misunderstanding. I always try to avoid the word "definitely", and for a reason. Actually i wasn't trying to contradict anyone's opinion, that's why i used "according to me" after the phrase "cost-effective". And i didn't make the definition of an ideal division, since i believe it's a relative thing. But it was you who defined it as "definitely not", without regarding what i might be thinking.
Maybe i wasn't very clear about this in my very first post. I noted that there was never a 4-battery rule, that it was rather a strategic decision. My "cost-effective" isn't only the operational level combat effectiveness of a battle formation, but also the strategic level, including the cost of the units, gathering them, putting them into battle, supplying them, frontage etc..
To give you an example of what i might be thinking: Suggest your division (the same number of infantry and artillery elements in it) is fighting in the enemy territory without access to a depot and it has to enter a series of big battles. According to the frontage rules, you have the chance of putting all of your elements in battle, so you have a high strike force. Since infantry is targeted before your artillery, your chances of losing them before anything else is higher. That can leave your artillery virtually defenseless in the next battle. Maybe a division with 4 artillery batteries might not be able to put all of its infantry into the battle in the same round, but the remaining infantry can commit into the battle to defend your artillery batteries, after the already-commited in infantry rout.
*Think* what role you want the division to fill. You don't have to think every time what you want to have in it. Come up with a set-up that is for an indy-division, and another for a corps division. When you decide you need an indy-divison, recruit the elements needed for it; when you need a corps, recruit the corps-divisions and assets you need for that.
There is no no-brainer set-up for divisons in this game; the game is slightly more complex for such. This is not after all a "RTS" game where you can just clickety-click without thinking a bit first
First of all, when there was a lack of information on some important points of this game, while people were still asking about how to form corps and divisions and CPs etc.., Runyan99 suggested 4 artillery batteries was a good choice, thanks to a hint from Pocus. No one ever claimed that there was a generic division formation, or a 4-battery division was better than a 6-battery division. But the suggestion was good enough for a start for most people, and experience showed it was not a bad choice.
Second, not everyone may have a chance during the game to make different types of battle formations, and some simplification can help.