The creators creators
that the people of Erf don't know very much about the XP-ing system.
In RL, the players of MMORPGs tend to be able to figure out how the game mechanics work. In effect, they work like physicists and experiment. They might hit the same mob 1000 times and vary their strength stat (say with a collection +str item) and see what effect it has on damage.
I wonder if the same thing happens in Erfworld. You could have people trying to figure out the game system by experiment.
If a side did this, it is not likely that they would share their knowledge with the other sides, so it may not be common knowledge.
Also, Parson's bracer fundamantally requires knowledge of the physics. When he is explaining his strategy of maximising their bonus while killing the enemy leaders to minimise the coalition's bonus, he said that he has been examining the game system via the bracer. (Presumably, he tried lots of different battle scenarios, to find out which one gives the best results).
Anyway, he obviously doesn't know much about the world, so the underlying equations must be built into the bracer. This could mean that it gives him the basic mathamancy knowledge of the world, that all mathamaners would have. Alternatively, it might combine the processing power of the electronics in Parson's watch with the exact equations of Erf's game physics engine.
This means that he could quickly carry out experiments in order to refine his knowledge of the game world (kinda similar to what he did with the bonuses). This could allow GK optimise general operations and in war logistics are very important (the whole "an army marches on its stomach" effect). For example, he might figure out how best to level units, balancing safety and speed or what kind of stacks would allow the rebuilding to go faster. Also, assuming rush builds are possible, there would be a balance between spending money (as that ties up Sizemore mining more gems) and just waiting.