Designed Distraction

In a film class we recently discussed a technique which some filmmakers use (the point of which I'm still not sure) which deliberately does not keep the viewers attention. Fassbinder used this technique in many ways to challenge the attention spans of the viewers of his films. Reading 20 pages of Ulysses took me two hours today and it often wasn't because I didn't understand subject matter, but because I found it very easy to get caught up in my own thoughts. I know this isn't a very analytic post, but it is something I'm curious about, because it's very possible that this is just my own fault, but if it's not, then it has to be deliberate on Joyce's part, in which case, I'm very curious about his motives. What benefit do we get from being in our heads just as much as Leopold's?