Normally I prefer going for long shots with several simultaneous hits on things by timing the shots, so hopefully I never get into trouble, but if it comes to close stuff I generally stay close, go deep and hide under the convoy, then when the escorts get bored or look in the wrong place, I sometimes come up and have a crack at them, the deciding factor usually being how many tubes and fish I have and how good I think they are. It requires a lot of careful listening on the hydrophones, but I think that's one of the fun parts of the sim to be honest.
If it isn't favourable, I'll feck off in the opposite direction. So neither one nor the other, but both, depending on how good they are.
Chock