From the same web, related to the Bismarck sea battle:
"Three Japanese fighters are spotted at about 2000 yards. The 5th Air Force had found that the Japanese could be discouraged by defensive fire from the bombers. Therefore, squadron intelligence officers often advised bomber crews to open fire at over 1000 yards . The same tactic would have been a waste of ammunition against German fighters in Europe, who would have pressed home their attacks at all costs. "