It is impossible to determine a universal rule for "what goes into" a board report and "how much detail" is provided.

Communications to the board, much like all communications, involve three core elements: the specific understanding of the recipient; the nature of the material; and the context of the sender.

If the board is unfamiliar with the content, then more information is required sufficient to give them the ability and confidence to resolve/adjudicate the issue.

If the material is "unusual" (e.g. an acquisition when the directors have never made one, or a new plant when the directors have never embarked on such a project, or off-shoring when all the previous activity had been on-shore), then it is reasonable to expect greater detail. Similarly, if there is a significant financial or risk dimension , then you should reasonably expect directors to want to fully understand the issues and that may require more information.

If the board has little "confidence" in the author or sponsor of a proposal (e.g. may be recently promoted, recently hired, etc), then the author of the report may need to convice the reader that there is a mastery of the issues. Where the author/sponsor is long-experienced and well known to the board, then such length may not be required.

To suggest a universal right or wrong way to write a board paper, and what to put in it is somewhat naive.