The wands will create as many objects or holes as you like. Once your sensitivity has been adjusted and you have an outline you like, simply click the wand again in another area to begin making a new object. Right-click to end object creation once all objects have been wanded.
Expand the Object View to watch the objects get created – sometimes a higher sensitivity will result in fewer objects or outline nodes, which is desirable. Other times, higher sensitivity can add ‘noise’ in the edge, or even fail to find a shape at all when the outline and background are similar.