No you haven't misunderstood the question.I'm not sure what you are getting at ban; the safe zone for a lightswitch will be ~80mm wide, while a fuseboard will be likely somewhere nearer 300mm, as that is the width of the fitting. Its just the outside edges projected vertically upto the ceilling....
Or have I mis-understood the question?
Have I misunderstood the answer?
In the illustration below of an FCU supplying a cooker hood you'd be happy for the cable to take the route shown?