I have a jig for ease of repetition, but to be honest it is only the boys that use it, I still use tube blocks on the surface plate to score a centre line, centre punch, hole starter then drill. If you stirred the drill like a wooden spoon you might be able to crack a tube, but I can't see a jig would be any different than drilling straight by hand, as long as the hole is dressed properly.
I have a jig for ease of repetition, but to be honest it is only the boys that use it, I still use tube blocks on the surface plate to score a centre line, centre punch, hole starter then drill. If you stirred the drill like a wooden spoon you might be able to crack a tube, but I can't see a jig would be any different than drilling straight by hand, as long as the hole is dressed properly.