The two models represent fundamentally different philosophies of learning. In the block model, which remains the dominant structure in most residency and clerkship programs, trainees rotate through a specialty for a defined period—often four to eight weeks—during which dermatology becomes their sole professional focus. Lectures, clinics, and bedside teaching are clustered together, and then the trainee moves on, often never to return to the specialty in a structured way. In the longitudinal model, by contrast, dermatological exposure is woven continuously through the training period, with learners returning to the clinic week after week, month after month, building relationships with patients and faculty and revisiting core concepts at spaced intervals.

The cognitive science underlying this debate is well established. The spacing effect—one of the most robust findings in learning psychology—demonstrates that knowledge reviewed at distributed intervals is retained far longer than knowledge crammed into a single intensive session. Interleaving, the practice of mixing different topics or skills rather than practicing each in isolation, similarly produces superior long-term retention and transfer, even though learners often feel during training that blocked practice is more effective. Koch and colleagues argue that these principles map directly onto the contrast between longitudinal and block curricula: the block model offers immersion and focus, but the longitudinal model exploits the memory architecture that governs how expertise actually consolidates.

The evidence base for longitudinal integrated clerkships extends well beyond dermatology. A 2022 systematic review by Bonnie and colleagues in Medical Education examined whether longitudinal training models succeed in entrusting medical students with independent patient care, synthesizing studies across institutions and finding meaningful support for the model’s capacity to foster autonomy and continuity. The Harvard Medical School–Cambridge integrated clerkship, described by Hirsh and colleagues in Academic Medicine in 2012, became one of the most cited demonstrations that students embedded continuously in clinical settings could achieve educational outcomes at least comparable to—and in several domains superior to—those of traditional block rotations. Studies of community-based longitudinal clerkships by Latessa and colleagues further showed that academic outcomes need not suffer when the traditional rotation calendar is abandoned.

Longitudinal designs have also proven their worth at the residency level. Kelm and colleagues, writing in the Journal of Graduate Medical Education in 2015, showed that a longitudinal ultrasound curriculum for internal medicine residents produced measurably better long-term retention of point-of-care ultrasound skills than conventional concentrated teaching. More recently, Clayton and colleagues described in JACEP Open in 2024 the implementation of a longitudinal interleaved curriculum for emergency medicine residency training, explicitly importing the principles of spacing and interleaving into graduate medical education. The dermatology question posed by the Baylor Scott & White team therefore arrives against a backdrop of accumulating evidence from other specialties that continuity of exposure pays dividends in durability of learning.

Yet dermatology presents a distinctive set of constraints that make the comparison nontrivial. The specialty is visually dense and pattern-dependent: diagnostic competence rests on the ability to recognize hundreds of cutaneous morphologies, from inflammatory dermatoses to malignant melanocytic lesions, and this recognition skill is famously sensitive to the volume and distribution of exposure. A block rotation can deliver high patient volume in a short window, which is efficient for building initial pattern libraries. A longitudinal model, by contrast, offers repeated return to the same diagnostic frameworks over months, allowing consolidation and refinement—but potentially at the cost of daily case volume. The trade-off between immersion and spacing is therefore not merely theoretical in dermatology; it bears directly on how quickly trainees acquire the visual expertise the specialty demands.

Continuity also transforms the relational dimension of training. In longitudinal models, learners follow patients over time, witnessing the evolution of chronic dermatological conditions—psoriasis flares, the slow response of alopecia to therapy, the surveillance of atypical moles—in ways a block rotation structurally cannot provide. This continuity is not merely sentimental. Understanding disease trajectory is central to dermatological decision-making, and trainees who see only snapshots may struggle to grasp how treatments unfold across months. The authors’ framing of the question as “continuity or concentration” captures precisely this tension: each model optimizes for a different ingredient of clinical competence, and the question is which ingredient matters more, and at what stage of training.

The research letter, published as a concise contribution in Volume 318 of the journal, does not claim to settle the debate with new empirical data—the authors note that no datasets were generated or analyzed in the study. Instead, its value lies in the synthesis: it brings the longitudinal-versus-block question into a specialty where it has received comparatively little systematic attention, and it anchors the discussion in the strongest available evidence from medical education research more broadly. The work was received in September 2025, revised in July 2026, and accepted in August 2026, reflecting a peer-review process that refined the argument over nearly a year before publication on September 4, 2026.

For program directors and educators, the practical implications are significant. If the cognitive science of spacing and interleaving holds in dermatology as it does in ultrasound training and emergency medicine, then purely block-based dermatology exposure may systematically underperform in long-term retention, even when short-term rotation assessments look strong. Hybrid designs—concentrated introductory blocks followed by longitudinal reinforcement, or longitudinal continuity clinics supplemented by intensive immersion periods—offer a potential reconciliation, allowing programs to capture the motivational focus of blocks while preserving the memory advantages of distributed practice. The Baylor Scott & White authors, writing from the perspective of internal medicine and dermatology faculty at a large integrated health system, position their letter as a call for dermatology educators to evaluate their curricula against this evidence rather than by tradition alone.

The broader lesson resonates far beyond one specialty. Medical education has long been organized around schedules that reflect hospital logistics and historical accident as much as learning science. As evidence accumulates that how time is distributed shapes what trainees retain, the structure of training itself becomes an object of empirical study. The question Koch, Staheli, and Parekh pose—continuity or concentration—may ultimately dissolve into a more nuanced answer: the optimal architecture of dermatology training is likely neither pure continuity nor pure concentration, but a deliberate, evidence-guided combination that treats the spacing of experience as seriously as the experience itself.

Subject of Research: Comparison of longitudinal and block curriculum models in dermatology medical training

Article Title: Continuity or concentration? Evaluating longitudinal and block models in dermatology training

Article References: Koch, R. S., Staheli, C. F., & Parekh, P. K. (2026). Continuity or concentration? Evaluating longitudinal and block models in dermatology training. Archives of Dermatological Research, 318(1), Article 391. https://doi.org/10.1007/s00403-026-04859-2

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04859-2

Keywords: dermatology, medical education, longitudinal integrated clerkship, block rotations, spacing effect, residency training, curriculum design, learning retention, interleaving, graduate medical education, clinical continuity, Baylor Scott & White