Imagine stepping into a neighborhood store during a typical evening. You pick up a few items and walk toward the checkout. One shopper stands there, items being scanned steadily. The line holds just that single person, and the process wraps up fast. You're through and heading home shortly after.
Here, the checkout zone sits mostly empty around the edges. Transactions flow one after another without buildup. Space remains open between the counter and entering shoppers.
Time moves on, and additional shoppers complete their selections. They carry baskets forward and take spots at the line's tail. One by one, the queue extends as each joins.
Now with four or five in place, the line occupies more floor space. Each scan and bag still happens at the front in steady rhythm, yet those toward the rear wait as the turns accumulate ahead. The brief stop stretches noticeably longer.
The store's flow alters bit by bit through these arrivals. Early comers pass through with little pause. Those following find a fuller queue, prolonging their position in line.
The checkout turns dynamic—from a near-empty quick pass to a lined-up hold—purely as shoppers gather gradually over the minutes.