Career Points

How to Get
You can get Career Points from winning battles, certain battles will also give some on a draw however most will not.

Politics
The earlier you max this out the greater the rewards.

Economy
Only useful when buying very expensive weapons on mass, and even then those weapons will last multiple battles and you have wasted a Career point.

Medicine
Decent, especially with a massive army.

You will save not only the soldier but their weapon as well.

Army Organization
Useful to check prior to key engagements.

Cramming in another brigade or just making them larger, if you can do it, do it.

In personal experience having brigades over 2000 is useless but you'll want the Brigades Per Division when you get a battle that will allow only one of your divisions to participate; ie: Shiloh, the more brigades you can bring the better. Leveling this up beyond 6 is a bit wasteful but if you want that massive army then you go for it bud.

Training
Very useful in maintaining high level brigades.

When you refit with veterans the divisions stats will remain the same, if a brigade gets tore up and say loses half its men the stats of that brigade will plummet when adding recruits. In my opinion veterans should be used on your crack brigades primarily but also to boost your other brigades slightly; maybe a 15-25% veteran to recruit ratio.

Or you have too much money and you only use veterans.

Logistics
If you like your artillery, you like ammo.

While not so much a problem for large infantry armies if you have a lot of arty ammo will always be in short supply; this will mitigate that.

Reconnaissance
Ok, it's your first time playing and you want to know what you enemy has in store for you.

With the scaling the game does for big armies even experienced players may be shocked to find the enemy has twice the amount of troops than the last time you played this battle.

I will not go into scaling there is a lot to it like Kills/Casualties, Army Size, # of Guns???. I am not going to data mine what exactly it is just know not all battles will be the same.