Given the recent surge in online sales, particularly accentuated by the health crisis in 2020 and 2021, companies operating in the retail sector have increasingly recognised the importance of business-to-consumer (B2C) distribution. Consequently, last-mile logistics optimization has garnered increased attention in both academic and industry contexts. In this study, we examine the relationship between the workloads of couriers and their proficiency in executing assigned services in a B2C last-mile and first-mile reverse logistics environment. Additionally, we evaluate the connection between service density in an area and the distance between warehouses and service points with completion rates among couriers. By analysing a dataset corresponding to the deliveries and collections made in Madrid in 2021, we identify significant and moderate correlations between the couriers’ workloads and service completion rate. It should be noted that the correlations of completion rate with distance and visit frequency to each area are weak, yet statistically significant.