Everyone has their preferences, but we don't consider HS a full-day park, even with all the additions. The catch is, you might not get to ride everything while you are there, due to tiering of FP and crowds. For us, it's a great park to split with AK or Epcot.
That being said, we did the early early opening (and we arrived AT opening, not hours before), and rode EVERY. SINGLE. RIDE. by the time they opened the gates. And some multiple times. We didn't do every show, because that just wasn't the plan for the day. We watched the SW live action show, Little Mermaid, and for some reason... the boys wanted to watch the Launch Bay *cough* commercial *cough*.
We went back to HS a month or so later, and only focused on the shows. We rode ToT, and I think that's the only ride we rode that day. We did a lot of pin trading and browsing stores. We split the day with another park.
I know you could find a way to spend an entire day there, as many do, but for us... that's not the case. Enjoy it, either way. I think it's fun to experience the parks in different ways. Our last visit to MK, we didn't even leave "the left side" of the park, we did a lot of stuff we rarely do and just soaked it in. One trip, we didn't ride a single ride...and just played Wizards, played on playgrounds, traded pins, and ate.