The length of time taken to write a book depends on many factors, including the author's writing speed, the complexity of the novel, the requirements of the publishing house, and so on. If it was a completely new story and was not inspired by any predecessors, it might take the author months or even years to write it down completely. However, if the novel already has a wide audience and has been researched and taken notes, the author may need more time to perfect and modify the novel. In addition, publishing a novel required editing and revision, which also took time. Therefore, the length of time to write a book depended on the author's specific situation and could not give a definite answer.