So using a no overkill feature would promote the use of weapons such as regular torpedos or carriers in full battleship fleets. Basically, if a ship, or ships, is going to kill an enemy ship with its weapons in a certain time frame, then no other ships in the fleet will target that same ship.
Say, if a fleet of 5 destroyers and a battleship, the battleship having carriers equipped. If the battleship targets the center, and one of the destroyers target the center, it will calculate if the salvo from the battleship will kill the ship in the center in a single round, if so, then the destroyer will target another ship close to the center.
I notice that when i played syntis, i was testing carrier modules, and setting each ship to target closest, furthest, and center, all ships of the same targeting method targeted the same ship, wasting thousands of damage that could have ended the pirate battle in a single round. The battle in this case lasted around 4 rounds of carrier strikes.