As competency-based medical education is adopted across the training continuum, discussions regarding time-variable medical education have gained momentum, raising important issues that challenge the current regulatory environment and infrastructure of both undergraduate and graduate medical education in the United States. Implementing time-variable medical training will require recognizing, revising, and potentially reworking the multiple existing structures and regulations both internal and external to medical education that are not currently aligned with this type of system. In this article, the authors explore the impact of university financial structures, hospital infrastructures, national accrediting body standards and regulations, licensure and certification requirements, government funding, and clinical workforce models in the United States that are all intimately tied to discussions about flexible training times in undergraduate and graduate medical education. They also explore the implications of time-variable training to learners' transitions between medical school and residency, residency and fellowship, and ultimately graduate training and independent practice. Recommendations to realign existing structures to support and enhance competency-based, time-variable training across the continuum and suggestions for additional experimentation/demonstration projects to explore new training models are provided.