Is the map useful for this particular task?
A model simplifies reality by leaving things out. A metro map can show which lines connect while distorting actual distances. That makes it useful for choosing transfers but less useful for estimating a walk. A model should be judged by the question it helps answer, not by whether it includes everything.
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Every representation makes a selection
A metro map may draw curved routes as straight lines and space stations evenly. Those choices improve readability, even when neighbouring stations are very different distances apart.
The map is not defective simply because it is simplified. Its value depends on its purpose.
A useful model preserves the features relevant to the task. For choosing a transfer, line connections matter. For walking above ground, street distances and crossings matter more.
The same principle applies to schedules, scorecards and diagrams. Before relying on a representation, ask what it includes, what it omits and which decisions those omissions could distort. A model can be excellent for one question and misleading for another.