It's silly to attack B17 or B24 or B29 alone. Pure and utter suicide unless you're a god at aiming and manage to hit them at 400 mph+ in a dive and kill at least one in one pass. The time it takes to set up an attack and reset is better spent looking for easier targets.
Nonsense. Killing heavies alone is relatively easy done right and the reset takes under 30 seconds. Even my fragile Spit XVI rarely gets shot down taking heavies out.
A fighter pilots doctrine:1) The number one responsibility of a fighter pilot is to knock down the heavies.2) No self-respecting fighter pilot willingly carries bombs unless forced to do so.