The AI is totaly incompetent with balancing the building decisions, ( among uther things), what i tried in my campaign, with 57 my own settlements and 7 of my client states, is i have 4 provinces, (12-16) settlements for food and military training, with high level infrastracture and with 2 full stack armies( from a total of 12) in the area, so when a rabelion is iminent, i moove the army at the spot, with forced march if needed, crash the rebellion. and all over again.
Thwe good think is that since the rebellion, it takes at leest 2 turns for the AI to mone the rebel army, after the increase of the unit naumbers.