For a terminal flow it is recommended that you create all of your messages containing general purpose variables in the variable message file along with the variable message.
For a nonterminal flow, until you become experienced in building flows it is likewise recommended that you create all of your messages containing general purpose variables in the variable message file. However, with a nonterminal flow you can keep messages containing general purpose variables in one or more general purpose message files rather than in the variable message file.
You should define general-purpose message elements only in a general-purpose message, not in the variable message.