It's amusing: one reason there is some much interest in the chronology is because Dad made it a bit challenging. He oversaw TSC but, like you, I don't think it's a very good book. I tried to not get into the details of it when it was being created and I try to avoid it now, because fans find it frustrating if they take it too seriously. I would like to believe that he was as careful as you suggest but I don't really know if it's true. As I've mentioned, he made a general effort but no one ever expected all of the books to be available all the time, as they have been, or that anyone would read them more than once. His ongoing success was something unforeseen and remarkable. It was also a era when the idea of a series that had to be read/watched in order was considered to be a questionable business practice. If someone missed an "episode" so to speak it was thought that they might give up or be dissatisfied. Until the very large bookstores appeared in the late 1970s and home video appeared in the 1980s there was no way for a company or creator to even pretend they could make every story available all the time. Each story had to stand on their own and to suggest more than a passing connection was considered risky.