On a side note to the ‘prefs’ approach:
Either the entire field content or individual nodes can be sent to Modelless Form classes for processing. This gives you a single field that can contain any number of discrete schemas and all the advantages of Validation, Rules and what-not. Or at the very least discrete and well defined Form to manage the stored data.
It is even trivial to take the Cakey-conventions approach of naming each node in the preferences.prefs column to identify the Form Class that should handle its contents.