Each time measurement considered 15 order plans selected by the Traffic Office of the company in collaboration with the authors. The selected plans were representative and included a large number of products, so that the analysis of the obtained time schedules yields reasonable and reliable conclusions.
The number of orders in the studied plans ranged from 5 to 17 per plan. To allow comparison between the picking times measured for items of different size, the results are presented as the measured time over the volume of the respective item, namely in minutes per cubic meter.