I make the following assumptions:
A typical Erfworld Warlord has access to the following:
Total knowledge of the units produced and/or used by their side (can directly see the stats)
Good knowledge of the units that his side fights (that is, all the local oppositions units)
- by good, i mean a general idea of move, attack, and defense in broad parameters, and any obvious specials like flight or natural mancy.
- does not include hidden or synergistic talents. Ansom specifically had to know to ask how to do the Dance Dance Revolution with the Archons, and was either wholly ignorant of, or contemptuous of the Archons anti-Foolamancy powers despite the presence of a Foolamancer on GK's side and thus a legitimate need for those powers.
May or may not know of the even the existence of other kinds of units, and thus have limited to no knowledge of their stats or abilities.
So this typical Warlord could legitimately be surprised when Charlie or his Archons do an Ass Pull on them, if they have never fought before. This despite the fact that one faction at a minimum on Erfworld knows Archons inside and out (double entendre left as an exercise to the reader, along with requisite giggle or beavis laugh).
I'm sure various sides have tried to disseminate some knowledge, at least internally to their warlords. Build up institutional memory and so forth. But when everyone and everything depops the instant your ruler is killed, its hard to hold that over or to even take it by force.
Parson started with total ignorance AND a host of incorrect and inherent assumptions about Erfworld. Parson has demonstrated a willingness to apply modern learning techniques (the scientific method or some variant evidence based system) to correcting this ignorance AND a willingness to discard previous assumptions when faced with evidence, two things that are not 100% common anywhere. He also is showing a talent, I believe, towards integrating his learning over time with tactics that he has used, developed, or learned over a lifetime of tactical wargaming. Fer instance- he knows that ambush and retreat tactics in our world are Older than Dirt, but he didn't know how to pull them off in Erf because of the pseudo turn based nature of the world. So he set about learning what he needed to know to pull off a version of ambush and retreat.
The summer updates has Parson and Jack trying to eliminate some of Parson's assumptions too. Parson was going very generic- Heavy Flier with such and such, not Dwagons. Thus, he can quickly apply broad categorical assumptions to a new unit, and then make decisions regarding it, and only really need to adjust to unique quirks if they exist and as they are revealed.
As to Erfworlders, some have a creative and adaptable side, some don't.
Ossomer seems both kinda Stupid and also wedded to some version of The Book. He knows how things are supposed to be done and has no interest in trying to change them. Ossomer would and was a terrible Chief Warlord, and GK should probably have left him in charge to make their lives much easier
Ansom is also at least engaged to The Book, but has shown tactical flexibility (if not strategic flexibility). He is smart, but is/was blinded by arrogance which limits his ability to learn for other sources.
Vinny lacks the arrogance but also seems to need to be prodded into actually thinking- he smart but either lazy or incurious. However, once presented with a tactic he grasps its essential nature very quickly indeed, and if properly motivated could be threatening. Then again, I may be doing him an injustice- he is not a Chief Warlord and so his smarts and curiosity may be irrelevant most of the time due to politics and command authority.
Trammenis is still kind of unknown, but snippets we have gotten suggest that he is perfectly willing to throw out The Book (use heavies instead of Command led Infantry masses? unthinkable!) and to do so on his own initiative rather than being prompted to do. Trammenis is much much more dangerous an opponent than anyone else Parson has faced.
Jillian is a blunt object in search of a nail, has maybe two motivations, and can be led by the nose if you actually understand her. Jillian is only a threat to herself and her side, except when she has the backing of much nastier intelligences like the Don and Charlie. I might be biased there.
Sylvia is a red headed goddess of Rage and War, and I would not presume to judge her on such crude measures as intelligence or adaptability.