You have Showtime that comes with your cable and as such, your Showtime Anytime includes ITN.

Yes. The Showtime Anytime app or webpage that came with my cable subscription (verizon fios) right now let's me stream just the latest episode (ep. 4 with clips from week 3).

I couldn't watch it for free on Amazon Prime (though it did say for the just latest episode "Watch with Showtime" (compared to other episodes where it's "Not Available". I haven't tried on other devices (and don't have apple tv). There seems to be a showtime on amazon service (above just the normal showtime included with amazon prime).

Yes I hate all these walled gardens and the lack of transparency on how to watch something, especially with so many similarly named products (Showtime Anytime, Showtime Streaming Service, Showtime on Amazon. And really NFL and showtime, I can't stream week 2's episode this week if I wanted because week 3 is available -- are you trying to encourage piracy?