Deciding a scale (or having a rough estimate for it) can be helpful for designers when first beginning a fictional world. Both small- and large-scale projects have their own benefits and drawbacks. For example, often internal consistency is easier to manage with smaller scaled worlds. In addition, worldbuilders may wish to employ different strategies when constructing worlds of different dimensions. Top-down approaches are often used for large scale projects, for instance.

Small-scale worlds are generally easier to manage and develop in detail, but they may lack the grandeur and epic scope found in larger settings. In addition, expanding a small-scale world into a larger one at a later time can be challenging, as the original design might not seamlessly integrate into the new, broader context. This is especially true because the inclusion of new farther-reaching fictional elements has greater potential to cause issues with internal consistency. Because of this, designers building at small scale may wish to have a framework or rough idea of the larger scale elements of their setting even if they are not including them currently.

Over time, worlds tend to sprawl and grow in scale. Worldbuilders find new ideas, concepts, and elements they want to add. For published worlds new installments are added to the canon. While expansive worlds are not necessarily a bad thing, they can be difficult for designers in a few ways – organization becomes increasingly problematic, the potential for issues with internal consistency is magnified, and just fitting together and remembering the sheer amount of information becomes a hurdle.