Halliday & Matthiessen (2014: 92):
… if a clause is organised into two information units, the boundary between the two is overwhelmingly likely to coincide with the junction of Theme and Rheme.
This might be true if we ignore conjunctive Adjuncts as textual Themes and comment Adjuncts as interpersonal Themes:
// However // information boundaries are highly likely between textual and experiential Themes //
// Actually // information boundaries are highly likely between interpersonal and experiential Themes //