At first when I saw that sentence I thought the preposition ON was related to the verb focus, but at a second and third analyzes I sort of notice that focus is not being used as a verb in this sentence but as a noun, so that explanation doesn't apply. I thought then that maybe ON was related to the verb redirecting but couldn't find any instances when this preposition is used with that verb. So my question remains, why focus ON TO, when only TO would have conveyned the same meaning?
Speech is not always uniform or perfect or perfectly grammatical as one might expect it to be.
One phenomenon that occurs is switching horses in mid-stream (in the middle of a sentence)
- Let's redirect our focus to the second list of issues.
- Let's redirect our focus from or on viruses to bacteria.
Yes, one focuses on something. But that does not make focus followed by on into a phrasal verb.
- What did you focus on at the meeting? means:
- We focused on various subjects. on various subjects is a prepositional phrase.
So, no, it is not a phrasal verb per se. He focused the camera on the model. Thus: He focused on her. It is usually a prepositional phrase.and sometimes the phrase disappears: What did you focus on [at the meeting]? has this meaning = On what subject did you focus? Anyway, in speaking, I can see why a speaker might say "redirect your focus on to what is working". This is a typical phenomenon in spoken language.
A speaker might very well link to focus on [some subject] with redirect focus to something. It is not a mistake per se. In writing, it would probably be edited to to or on.