Like others have said; usually, you know if you want to turn left or right. Your opponent will have to do some PRETTY crazy stuff to make you want to change that.
But changing speed . . . that comes in handy a lot more often, partially because it's much more difficult to predict the speed of an opponent's maneuver than it is to predict the direction. You might know that they'll move forward, but how far forward? Juno's ability gives great range control; plus, it applies to all maneuvers, and not just banks.

