True, and I do that if time permits it (often doesen't!) but the groove is no weaker than the thread that the same tool cut, only difference is that the thread is a helix so has one pitch of the thread higher than the root, but the root is still the stress riser anyway. Main point here is still, not a lot of major advantages to the CNC tool pullout as far as strength, but it is really cool and has a neat appearance.