Netflix's business model is ultimately all about subscribers.
That's not to say viewing numbers are not important however.
The more interest a movie/series/documentary generates there is a knock on impact of people wanting to subscribe to view it, or retaining a subscription they they may otherwise have rescinded.
Irrespective of what people feel about H&M it's pointless to deny these programs have generated a lot of interest.
The unknown is what peoples perceptions are of H&M having watched it. I suspect people already polarised for/against won't have shifted their position, but for "neutrals" who knows?
The problem for H&M as I see it, is that the interest isn't in them per se for most people.
It's about their relationship with the RF - one which is now tenuous at best.
Once they have finished this series and read the book I'm not really sure what H&M have to offer that would generate a similar level of response and re-hashing the same grievances about a family you are no longer in contact with isn't sustainable from a PR perspective - not only will people lose interest, it's also not a great look not to be able to move on and risks marking you look both greedy and unhinged (Samantha Markle take note here....).
The other concern I have is the cost to H&M not only wrt their relationship with his family, but relationships more widely.
It's no secret they both have ambitions to move with the great and the good.
However there is already some evidence that not everyone is keen to be seen in their orbit and the people happy to participate in this documentary have hardly been high profile.
I do question how I would respond to a couple prepared to tell all for money (and H made clear in the OW interview that approaching "the streamers" was as a direct result of C refusing to continue to pay their working allies from the Duchy of Cornwall income) if I was a high profile individual.
Would I be issuing the invitations to dinner if I felt there was a risk that my status/public interest in my life might be used as the RF's has been to generate the next output for sale?
So when considering the success of this documentary, I think it's worth considering the cost which might be more substantial than some people appreciate.