It is little appreciated how much the physical layout of an operation influences the way the process works. This is true whether the process is manufacturing, distribution or paperwork. If distances are great and movement is frequent, batch sizes will tend to be large.
Nobody wants to move things frequently and over long distances one at a time.
Large batches will lead to increased Work in Process, tie up critical resources for long periods of time and lead to a reduced ability to meet customer requirements. A manufacturing company trying to improve their process analyzed how individual parts flowed through their process. The product traveled over four miles inside their facility from start to completion. The process took over 1300 elapsed hours to complete. The product batch was counted 16 times.