Given our Productivity perks, when it comes to Simple or Difficult projects, there is only 1 truly inefficient AP investment level.
The progression goes like this:
0 AP = 0
1 AP = 1 (+1)
2 AP = 3 (+2)
3 AP = 5 (+2)
4 AP = 6 (+1)
5 AP = 8 (+2)
Ranking them by efficiency from most efficient to least looks like this:
3 AP
5 AP
2 AP tied with 4 AP
1 AP
Of note is that it is equally efficient to do a single 5 AP action as it is to do a 3 AP and a 2 AP action. In fact, these two options are the most efficient options possible.
The least efficient thing we could do is five 1 AP actions.
The second least efficient thing is three 1 AP actions and a 2 AP action.
Seeing this vote hurts my soul in the math.
It can be improved like this:
[X] Plan: The Productive Gift Giver
-[X] Helter Smelter: You're sure there's a way to more efficiently produce more Adamant, but as it is you can create at least one more smelter to increase your overall throughput. Having one work while the other recharges for instance. You can at least make one or two more before you start feeling as if you're running afoul of the Rule of Pride. [Cost: 3 actions, 1 Voidstone] Productivity Like No Other will proc. +1 Bar of Adamant every Turn instead of every other Turn. (Will count the turn it was done on) Overflow will only add progress to the next smelter and cost another Voidstone. 2 Actions
-[X] [Difficult] A Higher Standard Pt. 1: You've gazed upon the face of the Ancestors a lot in the past few years, especially when you were making your alchemical flame spitters, and it's inspired you. A banner to rally behind, something that dwarfs will look to and fight all the harder with it at their back. A banner worthy of the hold of Kraka Drakk to be held aloft with pride by an equally worthy standard bearer. [Cost: 1 action] If a rune you want requires special ingredients that you don't have access to I will alert you. 2 Actions
-[X] Master Rune of Grimnir, Rune of Valaya, Rune of Spellbreaking
-[X] [Simple] The Underway: Otrek is in less of a rush to complete this. The Holds of the North are not waylaid by enemies and are aware that with the way the weather's been, an Underway route is the only reliable way for them to stay connected. [Cost: variable normal and apprentice actions] Productivity Like No Other will proc. 2 Progress per action, 1 progress per apprentice action. 21 out of 30 Progress. 7 progress a turn regardless of input. 1 Action
This way, the Action we would have spent on the Banner next turn can be spent on the Dowry instead.
If that change is from 3 to 4 then it's a neutral shift.
If it's from 2 to 3 or from 4 to 5 we actually get an extra action's worth out of it.
Either way, this way the banner completes this turn with + 1 overflow it wouldn't have otherwise gotten.