Heroes & Generals has a lot of the same population issues the Naval Action has.
If our map unlocked the way theirs does, I think it result in fewer uncontested port battles.
If you attack and capture Port A you can then attack Port B or Port B/C or Port B/C/D depending on the importance of the port. Ports that branch off to multiple ports should be those with great strategic importance. Also, if Port A is captured then enemy will know that the attack be at 1 to 3 other ports.
PROS: Defenders better able to guess where the attack will come, and defend.
CONS: Limits player choice in regards to strategy.