This system was created with the support of the NRA because it was intended to be as close to instant as could be managed. The 3 days and out rule was designed so that the feds could not prevent the law abiding from buying firearms by merely refusing to process the checks. Now comes Walmart with this policy.
It has never taken more than 15 minutes to process me, but my younger brother, who is at least as law abiding, has had to wait out the 3 days a couple of times. Why should he be denied the right to buy a gun if he qualifies?