"4. Typical engagement distances against various targets.
Tanks armed with the 122 mm gun did not see much combat. They were mainly used for defensive purposes West of Tarnopol. Tanks opened fire at enemy tanks 2200-2400 meters away. During a single battle, Senior Lieutenant Makogonov's tank company destroyed and burned 17 Tiger tanks with direct hits. Of those, 8 were destroyed by Junior Lieutenant Pankov, 5 by Junior Lieutenant Pchelin, and 4 by platoon commander, Lieutenant Romashin."
As you can see, the IS-2 was quite effective at large distances, as the non-combat tests suggested.