Is it smart for a state constantly at war to hive together in same corner in ROC?

For ROC (seasons 1 - 4) you will mainly be in danger from other states. It is a good strategy to place your AC1 in the corner and surround it with other alliance AC1 buildings, plots and structures. This will make it very hard for invading alliances to reach your own AC1.

If you suspect though that other alliances from your own state will want to start wars with you during ROC it will be best to avoid them. A truce during ROC will be better for both of you though.