I have kind of taken a different view these days.
I don't care if it takes multiple torpedoes with multiple attacks against ships as this was what happened historically. If you look at the ship sinkings on
www.uboat.net you will see this is a normal thing and just part of the way of the uboat effort.
Difficult I know as real life is complex and many get limited time on their computer and probably don't want to spend hours of computer time to do a 6 hour chase after their first torpedo attack failed, then go around get ahead of the target and try again.
If we all tried to do the game religiously to history we would probably get fired from our job.