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The term "executive summary" is typically used in the formulation of a business plan. But it's a good idea for an individual, especially an executive, to have one too. This is different from the 2-3 sentence header I recommend candidates put at the top of their resumes.
In this new case, an executive summary is a paragraph (or two tight ones) that tells your career story, highlighting where you started, how you developed, and where you are today. It should convey motion and advancement and define your professional/industry point of view. It shouldn't list wins or clients; instead, it should describe your overall achievements. Think of it as if you were in the back of a deck launching a new product or business, and you’re an advisor in that launch. How would those 1-2 paragraphs read?