Sadly they could have been far more effective if the German high command had the slightest idea of how to use them and accept the risk of their loss in such an operation.
I do not agree to this opinion.
As per 1938 it became visible that a german fleet was faced with a considerable superiority of their likely opponents in every single class of ships.
Germany had a longer way to access trade shipping than their opponents (requires more fuel)
For the british side an actively attack on the contained german ships is not necessary.
It is likely that every german attempt for an attack is detected at an early stage.
Encounters with enemy capital ships ar more likely to happen in considerable distance from own bases-even slight damage may cause a total loss.
Enemy capital ships are likely to be screened by a considerable amount of torpedocarrying vessels and aircraft . Wheras such protection is almost impossible for the Germans from range considerations and lack of carriers.
This fear has been expressed in a memorandum report even before the war began.
Loss of Admiral Graf Spee and Bismarck are strong confirmation for this fear. Against Bismarck the Royal Navy deployed almost sixty ships and several long range aircraft(without US Coast guard and "fishing vessels" used for reconnaissance).
As the war progressed, the chances for the german side for succesful Actions shrunk, because of a growing air superiority in reconaissance and air attack capabilities.
The german side had no counter, as the ressources required for overcoming allied superiorty at sea had to be used in the main theaters of war. So they put only the absolute minimum of own forces needed to bind allied forces in a remote area.