"The executive summary is usually no longer than 10% of the original document. It can be anywhere from 1-10 pages long, depending on the report's length. Executive summaries are written literally for an executive who most likely DOES NOT have the time to read the original.
--Colorado State University: Writing @ CSU
"As its name suggests, an executive summary summarizes, or reviews the main points of, a longer document or report for a reader that does not have time to read the entire report. An effective executive summary analyzes and summarizes the most important points in the paper or report, and will often make a recommendation based on the analysis. Executive summaries are “stand alone” documents that are almost always read independently of the reports they summarize." --University of Maryland