So for instance, if you have 14 Janissaries, you can't form them up until you make one more. If you have between 17 and 35 of them, you'll be able to make one formation of 15 and the others will go unorganized. The leftovers can be thought of as replacements, perhaps. The economy is more important in that gold must be spent to maintain units. If your stock of these materials is exhausted, your forces may become helpless in the face of the enemy.
Mercenaries are expensive to maintain but quick to create in a pinch.
Resources do not run out. Though this may not be realistic for such items as coal or gold, this is more game practical in that these resources are, to an extent, an abstraction representing many other resources of fuel and metals. More appreciated is the fact that the wood is not exhausted. Trees grow back. Multiplayer support Choose Multiplayer from the main menu.