Background: This study aimed to objectively evaluate the impact of the gap in surgical practice caused by COVID-19 on surgical skill decay. Methods: This retrospective cohort study enrolled 148 cases of adult patients who were qualified for elective or urgent laparoscopic cholecystectomy. This study compared the period of nine months before the pandemic outbreak and nine months after the end of the pandemic. We analyzed the duration of surgery, the number of intraoperative adverse events (IAEs), postoperative complications (PCs), and differences between the surgeries performed by residents and those performed by specialists. Results: The number of IAEs did not differ significantly between groups (after COVID-19 (AC) and before COVID-19 (BC)). A difficult gallbladder (DGB) was associated with an increased risk of IAEs during surgery in both groups (BC:OR = 2.94, p = 0.049; AC:OR = 2.81, p = 0.35). The multivariate analyses showed no significant differences in IAEs or PCs when the residents performed surgeries compared to specialists. The average duration of surgery was significantly longer in the post-pandemic group (BC–102.4 min vs. AC–119.9 min, p = 0.024). Conclusions: Measurable determinants of surgical skills are the duration of surgery and the number of intraoperative adverse events. By defining this indicators, our study objectively shows that the reduction in the volume of surgeries during COVID-19 resulted in a phenomenon known as surgical skill decay.