First, I apologise for this post being a bit long, lol.
I do agree with you Tsed. There were technically multiple types of flak, but in general, when people think of flak, they tend to think of the cloud of metal shreds. Also, the term Flak, comes from the german word Flugabwehrkanone, or aircraft defense cannon, so yes, it does refer to many types weapons and rounds.
During WWII, HE Flak rounds were not viable until later in the war when proximity fuses came into use. According to files from the end of WWII, the proximity fuse, while being worked on by the Nazis, was never put into service by them, and the credit goes to the Allies for actually implementing the fuse into its anti-aircraft and even some anti-personal artillery rounds. Without going into a ton of detail, the Nazis where working on the fuse, but in 1940, Hitler declared any research project not expected to be finished within 6 months was to be cancelled, the project was shut down untill 1944, too late to be completed and implemented by the Nazi forces.
Prior to that, a round that relied solely on the explosion itself was relativley ineffective since , for instance, in the earlier bombings of French occupied and some German factories, flak gunners could not reliably determine a bomber formations exact altitude since the bombers where known to randomly raise and lower their altitude just prior to the bomb run. Due to this, the flak gunners relied on a tactic in which they would literally attempt to fill the sky in roughly a dome shape with flak rounds. This is an obvious tactic since, if you can't exactly determine where that plane will be when your shell detonates, it would be much more difficult to bring it down, where as with a round that places a "cloud" of metal that hangs in the air for several momeents, even if you don't get it exactly right, it is still more likely to inflict some sort of damage to the formation.
Anyway, I digress. I would assume that in the future, with combat in space, any sort of anti-fighter weapon would be much more advanced. Eitherway, I would assume that perhaps, a capital class ship would have lasers or small missile turrets to deal with fast moving fighters. I would believe that, due to the manueverability and speed of these much smaller craft, they would leave any sort of flechette round only viable for anti-missile defense.
