On a busy line, stability can vanish when the first surge compresses space, timing, and attention at once, so cartons arrive in uneven waves while the curve begins to sound harsher than the straight run, and the curve becomes the place everyone watches. A supervisor watches the lane because one irregular entry can slow the next ten items, especially during changeovers when upstream flow becomes less predictable, and when a box enters slightly off square, it skims a guide, rotates, and invites a rapid correction in tight areas where hands drift near motion and footwear steps around clutter. Training helps, yet pressure reshapes judgment faster than reminders can during the moment in real time.