One figure, once: what the shift book teaches about usability

The shift book of a container-glass production is the screen that stays open longest. It has to carry faults, maintenance, reports, tasks, photos and the handover. Over time that task produces a collection of bars, cards and indicators, each of which made sense on its own. Nobody built them badly. They simply stopped fitting together.

The finding was not that a function was missing. The finding was that the same figure stood in three places: in a status card, in a statistics element and in a pulse bar. Each was readable on its own. Together they created the impression of several truths — and the shift had to decide which one counted before it could even begin.

The rebuild removed nothing that was missing. It consolidated: one context bar for day and shift, four key figures that double as filters, and filters that carry their own count. What used to provide orientation is now the number next to the button. The domain paths are unchanged — capture, report a fault, document maintenance, complete a task, attach a photo, hand over the shift.

A second point is less visible but more important: the shift book is now built from parts rather than from a page that keeps growing. Context bar and key figures are separate pieces with their own checks, not the next section in one file. The reason is not elegance but maintainability: a screen that can only be understood by reading all of it does not get developed further. Eventually it gets worked around.

Third, speed. Five dialogs sat in the document permanently, although they are almost never open. They are now built when they are needed. For people that is a gain in speed. For screen readers it is the condition for the page being read out at all: what is not in the document is not announced.

For technical decision-makers: the question is not whether an interface is complete. The question is whether it shows the state exactly once. An interface that offers the same state several times looks usable and is more expensive in a shift than one that shows a single figure and leaves the action in between.