It's a learning curve, very similar to learning that I
MUST SAVE OFTEN during the game least I suddenly and unexpectedly die.
I now routinely save (or try to remember to do so):
1) during every long-distance transit (about every 1000 nm)
2) after reaching my assigned objective or long-distance destination
3) after each sinking (unless in convoy)
4) after each convoy encounter
Being forced to repeat a patrol
(or a career
) due solely to my own carelessness and/or stupidity has a way of motivating me to pay more attention to the mechanics of the game itself rather than just concentrating on the tactics of my current patrol.