In my opinion game play would be much enhanced if the player could dictate the garrisons within their settlements. I notice there is a button we can push now to see the garrisons we have could that be pushed with another chance to add or delete units we wanted within the settlement. I am almost sure I remember one of the older games making us drop what we wanted for as garrisson or we had to disband units to improve the garrisons but if we could pick the units (that we had unlocked) and how many of each I think it would be a greatly improved game.