That's because "The Dark Knight" pretty much is David Finch's own self-contained little story within the larger context of the Bat-Family. Same with Tony Daniel's "Detective Comics". "Batman", "Batman and Robin", and "Batman, Inc" are all within the same continuity structure as is "Nightwing" thanks to it's connection to "Batman".
I finished reading Supergirl which I am going to stick with. I am actually enjoying this book more than I thought I would be. Nightwing was an improvement over the first issue but I think I'm on the verge of dropping it. Legion of Superheroes is being dropped, have no idea what Levitz is working towards now if anything. Red Hood I'm keeping...great issue and the dynamic is slowly forming between Kory, Jason, and Roy. Batman continues to be my second favourite book after "Action Comics". Scott Snyder is just awesome and Greg Capullo's art work reminds me a bit of Tim Sale's. Just awesome.