Automatic Symbols how do they work

For some features when you add the class it will automatically assign a symbol.

For example you add a feature called railroad it will automatically assign it a the general symbol for railroad

If you name a feature Highway Ramp it will automatically assign the Highway Ramp symbol.

Essentially if the name of the feature class matches a saved symbol name it will give it the symbol.

The question is: Is there a way to automatically assign a symbol to a feature class based on SubType?

For example. I renamed a feature class to Phantom (save symbol name) and it made generic symbols based on SubType.
I renamed a subtype to Highway Ramp and it still gave it a generic symbol.

Or better yet. Is there a way to automatically assign a symbol based on the Unique Values? What I would like to do is create a symbol that is actually a number. I can to it manually but that will be very time consuming.