Using definition queries, one can display different subsets of one dataset at different scales (ie, reducing the quantity of points shown based on some attribute as the user zooms out). This requires that each definition query has its own layer. When dealing with a map with a wide scale range, this may result in very many layers with the same symbology, but different definition queries. I would like to suggest that definition queries can be applied to scale ranges within one layer (or, a scale range can be applied to a definition query).
Ie. from 1:1,000-1:30,000, apply one definition query
from 1:30,000-1:100,000, apply another definition query
This can help keep the quantity of layers in a map down, and reduce duplication of symbology and label classes.
