I not sure of your wording, but if you where to use a Endmill after you drilled a hole and then reamed it, you normally end up with a better hole, the reason, the drill ( if not good quality, or sharpened correctly can be off the true position ) the Endmill would straighten the hole an machine it on position, the reamer would then follow that true hole better than a just drilled hole, sometimes this is a normal operation when wanting True Position Holes