The imprecision of the hydrophone combined with the slowness of moving about the stations trying to set up a hydrophone shot would seem to me to be a very risky torpedo shot. You would probably miss.
I have taken to playing 100% realism with every single option on maximum difficulty. This means no map updates. Everything has to be done by the player sensing the tactical situation.
I find that I have adopted a much more "run and gun" approach to fighting, and I believe that it is probably somewhat realistic to the way it was probably actually done. Historically they may have had a somewhat easier time in estimations due to multiple people working the solution problem and also they had a much better sense of depth perception and a sense of bearing and distance than we can get from a computer screen.
But I find that nearly everything about setting up an attack approach is an estimate. And in that regard, it's probably fairly realistic.
About the only thing I can know with any real precision is the bearing to target based on visual observation. I then eyeball the target to get an estimate to the Angle on the Bow, and then I can figure out in my head what the target's heading is relative to my own heading.
I drive my boat to a 90 degree intercept. I only very rarely attempt non-90 degree attacks. It's just too hard to estimate a good AoB.
Likewise I have taken to estimating target speed. Unless I have been given a radio contact with an exact convoy speed, I usually guess 7 knots for target speed. This is what most merchants sail at. Sometimes they are a little faster, sometimes a little slower. I close to within 1000-500 meters and fire close to the center of the ship. Usually this results in a hit. However, sometimes I incorrectly estimate the target speed and miss.
The days of aiming torpedoes for specific areas of a target are over on 100% realism.
Steve