What is the author's style in Journey to Ixtlan: The Lessons of Don Juan by Carlos Castaneda?

In this book's introduction, Castaneda explains that his relationship with Don Juan began in 1961 and lasted ten years. The body of the book is structured so that each chapter contains a heavy chunk of Don Juan's advice and philosophy. In each chapter, Castaneda provides weekday, month, day and times that events allegedly took place. Dates specificity is not really needed and often doesn't match up to the narration. The diary format coupled with the introduction that refers to his other two books is supposed to contribute to credibility. However, it does strike incongruous that in this book, Don Juan doesn't want to talk about hallucinogenic plants. The main action in his first two books cover his peyote, Jimson weed and mushrooms experiences and take place during the same ten year period between 1961 and 1972. Why does Castaneda report that Don Juan doesn't want to talk about plants, if he's already written two books on the topic as guided by Don Juan? It is possible that he wrote of his experiences out of sequence.