No, there is no spawn from thin air. If an enemy band comes from somewhere, then there is a camp that spawned it. The enemy spawn works as the merchants in town from what i’ve seen. The enemy camps have a unit counter and every time unit it increases. When a band is spawned it decreases the camps unic count. When there is a pray in sight the camps will increase their band formations and heavily drain the camps units. If the army near their camp is strong they tend only to spawn the usual scouts.
Now your party costs 318, that mekes most of your men nobles hedge knights swordmasters and other strong backgrounds. This is an extremely powerful mercenary group. There is nothing that could possibly end you at this point. My testing party was made up by extremely low upkeep backgrounds with a daily upkeep around of 150s. And even they were almost impossible to stop. Last few times I changed things up to see how it is to have a high upkeep army that has stats far above the one I had before. Still in progress but even now when half of the team is low lvl(1-4) there is not much of a difference, they stand their ground agains orc hordes and undead swarms. This is a management aspect. And I do like it. A low upkeep is absolutely valid, while a high upkeep is an overkill for now. You got to manage what you are capable of and what is above your paygrade.
A tipp to be able to sustain a high upkeep army. Go raid. Even without quests go and raid enemy camps, fight them and sell all loot. Take only the high profit jobs with 3k+ reward money.
And please, no please don’t do the spawn of thin air thing, that’s just plain stupid. The current system is fine-ish, the enemies have a base, they tend to stalk the settlements and roads. Why would you want no brain spawns to occur. At this moment, if you keep the surroundings clear of camps the roads are relative safe. Makes absolute sense. Just don’t ruin it. Caravans do already attract riders in the vicinity, they already tend to target the weaker enemies, and only rare caravans are stronger.