I prefer to operate ball head without touching any knobs, using friction control only. That requires a decent ball head (Arca Swiss, RRS, ...) with a tension control knob, which you preset once and rarely touch again. This knob is in addition to the main knob, which you use to lock/unlock the ball. Although you don't have to lock the ball when using friction control. That makes it two knobs. Only very basic "miniball" head, which lacks friction control, would have one knob.
Now having a separate knob for panning is handy in many situations.