Medical schools are increasingly reducing required contact hours and incorporating self-directed learning strategies, yet the impact of these curricular changes on academic performance remains uncertain. This retrospective cohort study compared performance on NBME-based organ system examinations across three consecutive pre-clerkship cohorts at a U.S. allopathic medical school that experienced different levels of required instructional time. Cohorts included 178 students and differed in total required contact hours from 306 to 412 h. Mean MCAT scores did not differ significantly among cohorts (510.4 ± 5.4, 509.6 ± 6.3, and 510.0 ± 4.9; p = 0.74). Significant differences in the proportion of students scoring above the national reference value were observed in the Pulmonology (p = 0.003), Gastroenterology (p = 0.020), and Endocrinology (p = 0.003) blocks; however, these differences did not demonstrate a consistent relationship with contact hour totals. Across cohorts experiencing different contact-hour requirements and concurrent curricular changes, examination performance did not demonstrate a consistent pattern corresponding to the amount of required instructional time. These findings demonstrate that lower contact-hour requirements were not accompanied by consistently poorer short-term standardized outcomes in these cohorts; however, the independent contribution of contact hours cannot be separated from concurrent curricular changes.