The conventional wisdom is to get army camp production to only 250%, or so because the AP is better spent elsewhere. However, I think this may be incorrect.

To preface this, I have already maxed out additional mercs. I have epic ACB artifact, and my army camp production is 260% so the real question is, Is it better to upgrade ACB to legendary or spend the AP and increase army camp production to 340%?

Both will add 80% (times 1.3 with the watch ad bonus) to my army production. Both will increase my draft production (I get 50% more armies from draft than from camps. And the fact that I get lots more armies from mercs than camps is no longer a concern

The AP cost is only 2400. Also, by spending the AP, I can always decide to not use the ACB artifact at all and the advancement will be equal to using the epic artifact all the time but will free up the bay for another active artifact. (Note I will still equipt the epic ACB when I draft.). Finally, if I spend the 2400 AP, I can upgrade a different artifact to legendary.

So, for the more advanced players, did you upgrade ACB to legendary or insane? Did you increase army camp production past 250%? Did you do both?

I upgraded Army Cache Boost to insane as my first insane, and I am very happy that I did.

The army caches and merc camps (assuming you maxed additional mercs) should give you enough armies that for all levels (except maybe some super levels?) you shouldnt have to bother with army camps or drafting at all :)

I built a legendary camp boost as my fourth artifact to carry over through super ascensions.

With this I don't bother investing in Increased Army Camp Production until much later.

Here "much later" means when I go after challenge levels, and I take it to +100% or so.

I have been thinking of doing that a little sooner, depending on how early map replays go.

I've read in one guide that going to 100% is the thing. IIRC that's only 250AP
Good for earlier maps in a run in particular clam requests, get a good start on a level.
Also good for challenge and battle I guess.

If you have really good army camp arti then I suppose no point of even that.

I own a leg AcampB arti (for 160%) and never invest into IACP at all...

... until I am shortly before super ascending and want to collect the challenge levels. Then I go for a total IACP (incl arti) of ~480%.