I do not like the term “executive summary”. It suggests that if you are senior and executive enough, you are somehow rising above the masses who are swimming and drowning in detail. Most executive summaries are over-summarised with buzzwords and hollow phrases.
Clients often ask me to write an executive summary of a presentation, and I usually say they do not need one. A careful selection of the key slides of a presentation is much better suited for the purpose. Nobody likes to read 2 dense pages of prose, flicking through a number of visual slides is much more interesting. As a result, the message gets across better and faster.