You're not alone here. My 2 cents of rant. Last night was the 5th (yes, fifth) time I was sent to Rabaul to "spy" on aircraft carriers. Not back-to-back, but once in every patrol.
But I can't complain much, since there is an upside to it:
a) every time the DD's present a slightly higher challenge;
b) sinking 2 carriers adds greatly to tonnage;
c) there is always an interesting convoy arriving at Rabaul bay on my way out, I just have to be quick about scoring a hit before the convoy "despawns";
On my 3rd "carrier spy" mission, a large convoy sailed into the bay. It was a pitch black night. While I was working to position my boat for an attack, fog came down too. I managed to hit a large cargo vessel with 2 torps, which weren't enough. So I fired a 3rd torp. Before the torp hit the target, the whole convoy "despawned"
How do I know, if there was thick fog all around? All the sonar lines slowly faded into oblivion. I moved into their last known positions, and there was nothing there. Boy I felt cheated.