Imho, all high caliber ninjas (either by stats or by talents) can cause 10-round fights. A sb kakuzu and certain fights with kushina, for example, will cause the same thing. So, even if you have distinct ninjas per field, you can still find yourself in 10-round battles.

Just want to add, I think some fights are long because of position stacking. Stacking at a certain point makes most ninjas pretty tough to killl. Even a p1 light main stuck in an immobile/chaos trap can last 10 rounds if stacked decently.