I should reword what I said. I have seen the Torpedo Bomber out patroling. Once there was four in a very tight trailing stack formation. I just haven't seen any sneaking in on a torpedo run as yet.
Now, with what you said about Sub AI, I am getting a paranoid complex about running on the surface. Specially running on the surface at high speed any time, day or night.
"Is it really worth the risk to run surfaced at high speed, traveling that 200+Km distance to intercept that contact report or not?"