Focus 70 percent on developing strengths: Effective leaders who reach their potential spend more time focusing on what they do well than on what they do wrong.
Focus 25 percent on new things: If you want to get better, you have to keep changing and improving. That means stepping out into new areas. If you dedicate time to new things related to your strength areas, then you'll grow as a leader.
Focus 5 percent on areas of weakness: Nobody can entirely avoid working in areas of weakness. The key is to minimize it as much as possible, and leaders can do it by delegating.