Agree if you find them already fighting, but what about if the tension is building up over a period of time, would you not recognise the warning signs that things were not going well, and perhaps about to go really pear shaped - then would voice commands / action either stop or avoid an incident ?
That's all good thinking you will pick up on the signs, I've seen it kick off with no warning at all with two dogs that lived together for 6-7 years with not so much as a growl at each other, these two would eat their food with the dishes banging against the others without any issues believe me