I've done some turning, mostly small bowls under 10". Have done some
practice spindle turning. I now want to try turning pens. I watched an
instructional video on pen turning and the instructor was emphatic about
drilling the hole in the exact center of the pen blank. I don't understand
why the worry. If the hole goes in one end of the blank and out the other,
everything will be center AFTER turning the blanking. Why the concern about
being centered initially?

The instructor was using a centering vise which is a neat tool but is it
really necessary??

Thanks,
Dave