Where 9.2-inch monitors would have served

Where would follow-on Roberts-class monitors armed with twin 9.2-inch turrets have been useful?

In amphibious, riverine, and coastal gunfire missions, including D-Day and Korea.

Amphibious assaults, riverine work, and inshore operations are the natural missions for follow-on Roberts-class monitors. D-Day offers an obvious Second World War use, while Korea provides a later setting for sustained coastal fire support. Their shallow-water usefulness and heavy shells matter more in those roles than speed or conventional fleet combat. The design would remain a specialized gunfire-support asset instead of serving as a substitute for a cruiser or battleship.