You over simply - depends on trans type, if auto it depends on stall speed, what carburetor name, what camshaft, other factors. My race car idles at 1500 in or out of gear.
To make a blanket statement isn't accurate.

Do I believe a locked distributor is correct for all cars - absolutely not.
To criticize a guy for doing it and saying he doesn't know how to tune is not fair either.