Was destroying an entire convoy unusual for Force K?

Was Force K's destruction of seven merchant ships at Duisburg an exceptional result?

It was the kind of complete result Force K sought, but Duisburg was exceptional for the immediate effect of losing so much fuel and ammunition at once.

Sinking seven merchant ships in one battle was the kind of complete result Force K sought after catching a convoy. Duisburg became especially important because the ships carried a concentrated load of fuel and ammunition whose loss had rapid operational effects. The surface force could destroy merchants and escorts together. Submarines could then threaten damaged or towing vessels during the aftermath.