So even the US during the height of the cold war couldn't do it?
During the cold war the US certainly had periods where it was able to launch multiple ships in a year, in an impressive fashion.
I'm not sure if they've ever had shipyards where they would assemble 5-6 destroyers in a single drydock.
For the record, assembling 5-6 destroyers in a single drydock is a reflection of national shipbuilding strength yes, but also on the specifics of the given shipyard in question. It's not an absolute indicator of awe inspiring industrial capability at the national level -- you can still be a very formidable shipbuilding nation without it.