Graduate medical education in the United States has been progressing toward competency-based training for the past 25 years, beginning with the Core Competencies. ACGME Milestones versions 1.0 and 2.0 further attempted to granularly assess the knowledge, skills, and behaviors residents should demonstrate to competently practice without supervision. Both frequent rapid and longer infrequent assessments form the core of assessing residents’ progress toward competency. Trainees may master competencies at different rates, making time-variable promotion and time required to demonstrate competency inherent parts of competency-based training.