A cursory reading of the book and its crude fictionalization quickly reveals the reality of the experiences related. This guy is not skilled enough to make anything up, and that actually serves to accentuate the book's reality. The word fiction is not synonymous with the word untrue. Some truths are best related within fiction. That is why Edward Beach chose fiction for his Run Silent Run Deep trilogy. If you want to know how to run a WWII sub, there is no better source material.
In TMO, if the escorts are around you can safely assume they will be on top of you.
Therefore, you have to outsmart them. I usually plan on an action which will take several hours. I begin my attacks at sunset to take advantage of the cover of darkness during the entire action.
The first attack is a compromise. I'm targeting the largest merchant, because I'm going to be shooting from a distance. I'd love to sink him but my primary goal is to concentrate the escort screen on my side of the convoy. I'll close to between 2000 and 2500 yards and shoot two torpedoes at the same target from outside the escort screen. Don't do anything fancy or try to hit multiple targets. Immediately after the torpedoes leave the tubes, turn tail and run. The escorts will dutifully charge your last known position, but you'll be out of there, on the surface at 3000 yards or so from the nearest escort.
Do an end around to the other side of the convoy. You have about 30 minutes. Now you have a completely unguarded side of the convoy. Press your attack close, hammer 'em hard and again turn tail to run before the escorts can get to you.
Rinse and repeat as necessary.
If the escorts do succeed in pinning you down, look for the sneaky guy that stops to listen to tell the others where to drop their greeting cards. Once he vanishes from sonar you can be sure he's stopped. It's time to set a torpedo or two for point and shoot. A Mark 18 is great for this. Speed zero, AoB zero or 180. Come to periscope depth, point the boat to put him on the zero bearing, press the send range/bearing button and shoot one quarter of the way back from the bow. That way if he hits the jets you'll still get him.
I find that a sinking buddy cools their aggressiveness enough for you to get away.