See and read Every Page is Page One:
Every Page is Page One is an approach to information design and information architecture that recognizes that readers may enter a content set at any point, and so ensure that every page in the content set can function as page one for the reader.―Mark Baker
This is thoughtful and generous approach: a real gift.
For training and technical writing it seems obvious: Yes.
For other writing it probably doesn’t seem obvious. In fact the answer probably makes us somewhat queasy.
However for other writing the answer is: Probably Yes, more than we like to admit.