In response to Veale's request, Netflix revealed that it uses an individual's decisions to figure out which part of the story to serve. That makes sense, of course. If a person retired from Bandersnatch in the middle of the story, Netflix would be able to remember the chosen path and serve the right branches of the story.
Netflix also summarizes all decisions made by users to see how the audience interacts with the story as a whole. The company said in an e-mail message to Veale that "information is being used to determine how to improve this storytelling model in connection with a show or a movie." Netflix did not reveal how long data is stored in relation to people's decisions.
It's probably not a big surprise that Netflix kept all sorts of data about people's interaction with Bandersnatch . It was the first time the company had chosen an adventure story for themselves. The resulting information will likely help Netflix decide whether to tell more stories in this format. However, it is a good reminder that companies collect almost every piece of information you receive, including seemingly harmless data points, and keep this information indefinitely without explicit consent.