When it comes to lightning strikes, the question is not how useful a lightning rod could be but how important it is for you feel safe by avoiding the possibility of any kind of damages or threats.
The lightning rod is a device of special utility, placed on buildings to protect them from damage that lightnings cause. Practically, what lightning rods do is they transfer the lightning current to the ground, guiding it away from the needed areas.
Another common question about lightning rods is whether they attract lightnings. In other words, if the existence of a lightning rod could make it easier for a lightning to strike the building on which the rod is located.
The truth is that lightning is indeed attracted by the lightning rod but by providing a controlled passage for it. It does not attract lightning strikes that would fall away anyway, nor does it cause any additional lightning strike. What it really does is simply “catch” a thunder that was directed at the immediate range of the lightning rod.
Without the lightning rod, the lightning would most probably strike the building, at some column, antenna, or other point, while with the lightning rod, the lightning is just passing through it without causing any damage at all!