Peter F. Drucker
Intelligence and imagination only set theoretical limits, but effectiveness is the specific discipline that converts those raw resources into tangible results.
Since time is an executive's scarcest and most inelastic resource, you should record where it goes, eliminate unproductive demands, and consolidate the remainder into large, uninterrupted blocks.
Rather than focusing on downward authority or specialized skills, you should constantly ask what unique contribution you can make that will significantly impact the performance of the entire enterprise.
When staffing or managing, you should build upon the distinct strengths of your team members, superiors, and yourself, rendering inevitable human weaknesses functionally irrelevant.