Jim Trinkaâs study of manager-employee surveys in government and industry reveals what surely must be best-kept secrets. For example, by focusing on âdeveloping others,â and âcommunicationâ competencies, managers can increase their overall leadership effectiveness by 50-60 percent. To drive his points home, he shows that 10 managerial activitiesâout of a possible 250âhave the most potential for delivering high employee performance.