My question is simple. Does the planning bonus for battle plans apply to give you higher organization and fight longer, or allow you to do more damage. I found the following quote, but it seemed a little vague.
"Units fighting according to battle plans receive a bonus to combat abilities, compared to those you manually order about."
In HOI3 terms a combat bonus is a multiplier to your soft attack, hard attack and breakthrough (on offense) / Defense (when defending).
So if your divison has 100 in soft attack
A general with level 5 (50%)
A general with offensive trait (10%)
Attacking a forest (-15%)
Planning bonus (50%)
Your divisions effective soft attack is then 100 * (100% + 50% + 10% -15% + 50%) = 100 * 195% = 195 soft attack.
The defender also gets planning bonus, dig in bonus, general bounuses, air superiority bonus, fort bonus.
My guess is defending in HOI4 is much easier than in HOI3 meaning a offensive planning bonus is a must.
HOI3 had some mechanic that bonues did not just add up, but had some weird math. Dont take the above serious. It is just an example.
Planning bonus does not increase organisation. It is merely a multiplyier to your weapons stats and ability to avoid getting hit by opponents shots.