One could always look at the .mis files and check out the exact shipping routes, but the paper map seems to be a pretty good guideline to the routes, even if it's not entirely accurate with RSRDC. During patrols I have noticed that the paper map is somewhat accurate at least what comes to the following routes:
- Japan - Singapore
- Japan - Palau(Koror)
- Japan - Rabaul
If the patrol area is somewhere in the western Pacific, then one will almost always run out of torpedoes because of crossing at least two of these routes. Especially in 1943 those seem to be some kind of troopship highways. If you're after tankers, then Korea Straits is a good place, and also the middle part of the Yellow sea. Just beware of the hordes of fishing boats in the Korea straits area. I bagged over 20 during my last patrol, with the biggest "fleet" measuring over 10 boats
