I have been playing around with the idea of adding journal entries into my novel to provide the reader with a first-person perspective. I would be able to use the third-person limited omniscient narrator to create a more objective and distanced experience, while giving the reader glimpses into the intensely lonely and emotionally tumultuous inner life that Mark experiences. If executed properly, my novel would then incorporate the best of both worlds.
I have many scenes that take place in the subway. I use it as a device to indicate the emptiness of Mark’s life: the most important and eventful things that happen to him take place in the subway with transient strangers. But not having a place to cut away to makes for a poorly paced and monotonous book. By using the diary entries, I can break up the novel in more interesting ways. I can also use it to intensify the feelings of loneliness by providing striking contrasts between the outer reality that Mark moves through and his inner experience.
The use of journal entries makes sense for Mark. He is completely alone, with nobody at all to voice his emotions and spiritual concerns to. It also gives the reader much-needed intimacy with Mark, something that is difficult to achieve with a third-person perspective of an intensely lonely young man who has nobody to have expository conversations with.
I may edit this post with more of my thoughts.