Purpose: While clinical reasoning in medicine traditionally values the ultimate goal of providing an accurate diagnosis of disease, insufficient emphasis has been placed on how students' decisions may affect their diagnostic efficiency. This study adds new empirical evidence about what makes students efficient problem-solvers in clinical reasoning. Methods: Seventy-five medical students participated in this study in 2015. The authors compared the differences in clinical reasoning behaviors between high- and low-performing students before they proposed any diagnostic hypothesis. The authors used the Cox proportional-hazards model to explore how certain characteristics of students and essential features of reasoning processes affect the life span of incorrect hypotheses. Results: High-performing students were more prepared than low performers to propose their first hypothesis. The more laboratory tests and hypotheses the medical students had, the longer it took for them to confirm a correct diagnosis. Male students tended to finalize the correct diagnosis earlier than females. There are no differences between the easy and the difficult cases in the aforementioned patterns. Conclusion: This study helps shift the emphasis away from a solitary focus on accuracy to one that considers the importance of diagnostic efficiency. The authors discussed two main take-home messages for physicians.