Everyone does things slightly different and if you are having fun that is all that matters.
With that, I spend most of my time 1939 to 1941. I never use magnetic shots because I have put a lot of work into a firing solution and don't want yet another thing that will "maybe" work.
When I say, a lot of time. In a recent patrol, I spent 45 minutes putting together a good setup for a submerged attack. Lots of observations. Scribbling on the F5 map etc. ....Only to find that when I did one of my observations near the attack decision time, I could see the flag on this ship...and it was a country I couldn't attack. That is part of the immersion in the game too.
If you decide at some point you want to obsess over the game after trying it out awhile. Take the time to learn how to put together a good firing solution on the chart/map (F5) command. It take time but once you figure that out, you might get into the habit of never using a torpedo on a target that isn't within 70-110 angle on the bow. I am a 75-100 person myself.
Don't worry if this doesn't make sense right now. If it some time the bug bites and you love the game, you will figure it all out.
