It depends on the nature of the tightening. Russ Carniak used to point out that the looseness in GI .45s was to comply with a test criterion imposed back when it was under consideration as the new service pistol. It had to withstand being immersed in water, then in sand, then keep on firing. Maybe some mud got in there as well. Ive forgotten. It was a criterion geared toward trench warfare, and Russ felt that unless we were planning to fight WW I over again, it made no sense to compromise consistency of the actions working motions toward that end. A properly fit gun would be tighter, more accurate, and feed more reliably than the original loose GI gun. It would not, however, be as tight as a wad gun for bulls eye match shooting.
In any event, if you buy a tight factory gun, like a Kimber, by all means run a couple hundred rounds of ball through it. People who want a little light lapping to speed things up often now load it with J.B. Bore Compound. This stuff wont cut enough metal to hurt the gun even if you fail to remove it all successfully.
If you get a gun hand fit for carry, it should already be lapped enough to be a little looser than a top target pistol, but still very accurate and reliable. I would always run the couple of hundred rounds anyway, but dont expect it to stop unless the smith has told you he left some of it tight enough to need the extra wear.
Nick