If we're talking about
Berlin Alexanderplatz, and how it seems uncommonly novelistic, only so much of this can be chalked up to its duration. Yes, its relative lack of brevity does afford it a certain immersion where the viewer is concerned, but it’s only in the movie being well rendered and dynamic in the first place that any of this means anything.
The idea that “long easily equals novelistic” (if you will) is suspect as there are plenty of TV shows or movies that go on, and on, and on, and have very little in common with the novel, at least the well written one worth reading. A filmmaking team can jam a lot of plot points, or “events,” or conflicts, or so-called “gravitas” from a book into a film, but it only amounts to anything meaningful if the
feel of the source material and the implicit truths are transposed as well, or perhaps, transmuted in an interesting way, creating something new. In the early cinema era there were a number of people who tried to adapt classic novels for the screen, but many got it all wrong because the films were overly busy on the plotting front but didn’t have much “life” in them.
Am not the biggest Kubrick fan, honestly, but I think he was one the money when he said:
A film is - or should be - more like music than like fiction. It should be a progression of moods and feelings. The theme, what's behind the emotion, the meaning, all that comes later.
Along these lines, Fassbinder understood what he was doing with Alfred Döblin’s book. He wasn’t cashing in on “hot IP,” pouncing on a pre-existing fan base, as many hope to do today. Instead he was trying to make a work of art that would stretch beyond the confines of formula and tacky commercial accoutrements, while still being consistently watchable. And he succeeded.