This topic comes up from time to time, usually related to matching the class breaks and symbology across a range of data sets with the same data type, but different values (usually from different locations or different time periods).
In ArcGIS the classification symbology is initially based on the min and max values for each data set, but that means that between data sets the same symbol may represent different class breaks, making direct comparison difficult.
I always advise people to use the import symbology function to create a uniform classification scheme and apply it to all data sets so they can be directly compared to each other.
Now as I'm pre parring to discuss this topic in a workshop I'm finding that I can't find any support for that technique or point of view on classifying data.
What's your thinking on this topic and do you have resources to point to where this is discussed relative to cartography or GIS mapping?