I was recently thinking on an old suggestion I made pertaining to the addition of an Attack Range option for Hired Units, and I thought of an even better way of reaching the end goal. The goal would be to enable more control over Hired Units in Guard Mode. This could be achieved by simply adding another slider into the GUI. Currently when a hired NPC is in Guard Mode one has control over its Guard Range. My proposal is adding another slider called Wander Range.
Here is a picture for an example:
The Wander Range would essentially control how far the NPC will travel from where it is (like Guard Range, Farming Range, etc.). However, the Guard Range would represent the farthest distance at which a unit will attack an enemy. If an enemy were to enter within the unit's Guard Range, the unit would attack. If the enemy were not within the unit's Wander Range, the unit would still attack, even if in order to do so the unit must leave its Wander Range. If the unit is not within its set Wander Range and there are no enemies within its Guard Range, the unit would return to its Wander Range.
For Example: I have a hired Rohirric soldier with a Guard Range of 32 and a Wander Range of 1 (or possibly 0). If an Uruk enters within his Guard Range, the soldier will rush to fight the Uruk. If the soldier manages to defeat the Uruk, then there are no longer any enemies within his Guard Range. Thus, he returns to the spot where he was. This could be very helpful in turning your Hired NPCs into guards.
If the unit's Wander Range is set higher than its Guard Range, the same mechanics would be at play. However, if the unit is attacked while not within its Guard Range, the unit will retreat to its Guard Range and fight there if necessary. One applicable scenario for this is having a large number of troops with a semi-small Guard Range and a large Wander Range. The units would spread out, and thus the enemy (player) might think it easy to attack. After all, the player can simply pick off troops one by one. However, the more the player tries to fight the more the units gather forces. It could also be used to have a particular section under heavy guard (Guard Range) while a player may not see that it is (because the Wander Range is higher, and the units are spread out). Once the plkayer enters the Guard Range however, all of the units from around rush towards the enemy to attack.
Edit: I almost forgot to mention: I was inspired to suggest the Wandering Range by Direranger50, as he used the terms "limits of [its] wandering" in his More options surrounding horns of command and unit hiring . While he may have had the same idea, I thought that it would be good to further the explanation.