Cannibalism a significant boon for logistics?

[Lord Revan]

The thing to remember here is scale a villager running for their lives will not pick just few small and easily searched areas but runs to which ever direction they think is the best meaning your search area is a circle around the village and a circle that keeps growing longer the search takes. Also the area near a village is probably not gonna 100% flat plains with only short grass on them, but rather fields and forrests that would provide plenty of locations to hide from your scouts and outriders.

Another thing to consider that in pre-industrial age most towns would be walled (town walls slowly faded away when cannons made them obsolete but that wasn't a quick process).

Also sieges tend to a long time and the defenders aren't really dependent on the nearby villages for suppplies (in fact IIRC it was common practice for people unwalled villages to flee to a nearby town or castle when an enemy came near and castles and towns tended to stack reserve supplies in case they got besieged) while the besieger would be dependent and sieges lasting months or even years were not unheard of.

If a seige is going on so long, why would the attacking forces bother? Why not just move on while the besiege d forces are immobilised and ineffective?

Move on to where exactly? another town that's just as hard to crack? Anything worth taking would demand a siege, the defenders can wait out while you exhaust your supplies riding about on the countryside, Hannibal did exactly that and was force to retreat when he couldn't force the roman forces to field battles.

[bilateralrope]

If a seige is going on so long, why would the attacking forces bother? Why not just move on while the besiege d forces are immobilised and ineffective?

Because, as soon as the siege ends, the defending forces are no longer immobilised.

[loomer]

It's not like there's a million books and articles explaining the rationale of siege warfare out there or anything. Mind you, I'm not convinced that the argument 'it'll cause sieges' is a particularly strong one against devouring your enemies, since if they have the necessary infrastructure for sieges (and they will if there's a history of war between you and them, since 'hide somewhere the enemy can't get to' is basically the first trick humanity figured out once war moved beyond 'have a bigger rock than they do') and eating anyone caught outside the walls is still free food for the taking in addition to all the other usual chevauchee and supportive food raiding.

What the orcs want may be a better question to ask. Is it actual conquest, to exterminate their enemies, or just to plunder and loot? Actual conquest will require sieges, but plunder and extermination? Chevauchee and cannibalism will do just fine for those, especially if you have no intention of actually holding the land. Devour the enemy's food and anyone unlucky enough to be caught outside like a swarm of locusts, poison the wells, and move on. Come back again yearly until the job is done, because the only way siege warfare can be survived for the besieged is if they have enough food stockpiled. Disrupt the harvests, ruin the farmland, devour the peasants, burn the plows, kill the oxen and horses and donkeys, burn the mills, poison the rivers and wells, and you reduce their ability to survive a siege because just to survive they have to start digging in to their reserves. This was the entire basis of chevauchee warfare - you ruin the support base of the fortified castles and cities and either force an engagement or, if they decide to still sit it out, let the inevitable disease that comes from swarms of refugees overpopulating the fortified holds coupled with the growing malnutrition and food insecurity break the garrisons from the inside when and if you finally do bother to siege them. The central danger of this is, of course, that the enemy may come out for a fight and actually win, but what kind of proper orc is afraid of a proper human smashin' battle?