Here's the first thing to remember about frame switching as it applies to copywriting:
All copywriting stories are "nested."
Matryoshka+doll-1In writing copy you inevitably create - at a minimum - one frame of reference: the one between your authorial voice and the reader.
In fact, copywriting teachers often advise aspiring writers to "talk" onto the page as if they're talking to a best friend, simply because that mental exercise animates that almost invisible frame of reference in the mind of the writer.* Writers who forget that frame of reference tend to produce artificial, corporate-speak copy.