keep troops in or out of my cities?

[SomeNick]

Welcome

Not sure what the intention of your question is but I'll give it a go.

If you stay in city/settlement >

Enemy armies that sit in territory boundary of settlement cause unrest to your population and affect income of the settlement.

There is a drain on the settlements income to support army. However Amry ensures hardly any unrest unless there are other factors involved ( enemy spies, public growth/health buildings required etc).

Settlements can fall to enemy army without a fight if your settlement is sieged long enough and you don't attempt to attack (sally forth) and break the siege.

That particular garrisoned Army also isn't contributing to the expansion of your faction, or gaining experience unless it is holding a part of your overall territory against the tide or invasion of an enemy faction.

An example for you would be my little Greek Cities campaign where I have sat a medium sized army of hoplites mostly, in Apollonia holding off the Romans for nearly 100 years now. In the meantime while the Romans have been concentrating on that settlement and dealing with my Navies pestering them everywhere, I have been eliminating Pontus and Egypt.

Armies outside cities reduce the presence/frequency of rebels and hold off enemy armies from sieging your settlements.
Also expanding your territory = Army experience = Gained Settlements = Income = More Armies.


Hope this helped : )