It was only now – a master’s degree completed dutifully, pointlessly; a commitment to a PhD made miserably, uncertainly – that she realized the world truly did not give one single shit whether you’d done your homework.
-- Narration / Kate (chapter 1)

Importance: Kate reflects on her academic achievements and how little they mean to her upon her arrival in New York. Kate’s commitment to academic qualifications despite her clear lack of enthusiasm or pride for their pursuit is used to highlight the extent to which she does what other people expect of her (she completes her metaphorical as well as literal homework) rather than doing what she really wants to do or being who she really is.

And Kate laughed a little, too, repeated it in her mind. Fuck the other Kate.
-- Narration / Kate (chapter 7)

Importance: Kate responds to Inez’s announcement that she does not care what has happened to the original Kate she was planning to...