In my opinion, on days even when the park is open for 12 hours, I would just stay in the park. I say that because transportation can easily add an hour each way. That's valuable park time. I would spread out what you are doing over the 12 hour period. Then once the park closes head out to the hotel or DS for dinner or something.
During our trip earlier this year, the parks had short hours like they are now since it was "off season". The original plan was to do a midday break then return. Once we saw the hours, and all the transportation hoops we would've had to go through, we just stuck it out. Things can be a little different with the parks now since they aren't as crowded, but still take into account leaving the park, getting to the transportation, the ride to the hotel, nap, getting back up, and traveling back to the parks.