The Book of Mormon says the Nephites were taught continually for three solid days, but that is not all. Just as he ministered to the Apostles in Jerusalem for forty days, so he ministered to his people in America for a substantial period of time. He wanted to make certain that they understood the program of the gospel under the new covenant. It must have been a genuine culture shock for the people to be told that many of the complicated and often minuscule requirements of the law of Moses were now obsolete.
Furthermore, they not only had to be told about wards and stakes, but they had to be carefully instructed in the requirements for a Zion society. The fact that these people began to set up a new Zion society within months after the visit of the Savior would suggest that he gave them a very concentrated, intensive, carefully-structured course on how a new Zion should be built.