There are 4 episodes dedicated to the battle rounds, 6 battles per episode. There won't be any montages as there are exactly 4x6 battles.
The Tuesday shows are only an hour long. They're not airing six full battles tonight. They'd need to cut a lot of the fat to air more than three battles in an hour.
But they don't want to cut fat, they want to fill three hours a week, they would add more if they didn't fear burning the franchise out prematurely.
If it were me I would want The Voice to be like The Gong Show was, once and out. And then you will have the judges interaction. But then it will be hard to sell that these people are something extra special over the singer playing the local bar or church this weekend.