B4 i think mightyme said trhis but when in wars ,the kages and sannins r sperated,like there should be a door surrounded around the kage and and a separate door around the sannins,because they r important and the villagers r all summoned to war and they fight,but they got 1 min to prepare,coz if thye r training,they will be weak and they will be defeated easily.When a villages villagers r wiped out,then ONLY sannins r let out to battle against the other teams villagers,then vise versa,the other teams sannins r let out,when 1 villages sannins die,then the great all mighty Kage is let out to Protect u...when he defeats the sannins,then the other kage is then out....and now u get what i mean.
Would this take long?Would it Affect Ur Training?well training will be simple,u can either nin,gen,tai train until the fight begins for sannins or kages,or u can stam train with ur weights.But if a bijuu has been summoned and u want it....then either surrender or there could be a warning sign that pops up for the kages(A BIJUU IS ATTACKING YOUR/ANOTHERS VILLAGE, ARE U SURE U WANT TO HAVE A WAR WITH THIS VILLAGE?).....now is this idea cool?or is a stupid idea that i just made?