That is certainly so - when the defending navy is overstretched and short of resources, having to cover worldwide commitments, as the RN was in 1940/41, before powerful naval allies such as the US entered the war. It is even more so when commercial shipping space is also overstretched and in short supply relative to strategic demands.Dave Saxton wrote: The surface raiders success was not measured by tonnage directly sunk. .
But don't forget that tonnage sunk adds to these existing problems.
The scattering of HX84 was a great success for the KM in terms of disrupting convoy cycles and in the need to provide adequate escort vessels to counteract surface raiders as well as submarines. But if two thirds or so of the thirty four ships had been sunk instead of five the scale of that victory would have been far more devastating.
Another factor to remember is that Scheers' success over HX84 made things more difficult for Lutjens on Operation Berlin. It would have been far better for the KM to have used the twins to attack HX84 instead. Indeed an attack six hours earlier by the twins could have sunk the whole lot.
The argument does come back to between a single raider in isolation, or a fleet in being able to launch a mass concentrated attack. The critical area is the North Atlantic supply line and to attack effectively you need not just a co-ordinated fleet of raiders working together but also in conjunction with U-boats and aircraft. And by aircraft I include strategic bombing of seaports and dockyards. In other words a concentrated strategy to win the war as opposed to an Emden or a Seeadler or a Wolf.