Life at USO/IOA is like anywhere else, much depends on your personal point of view and attitude (not to mention whether you are traveling with kids) and ambition.
While some folks consider "doing the whole park" as riding the Hulk, the 2 Dragons, and Spiderman, others can spend many days at the park, never ride a coaster and still find something new every time they go there. I have been there a dozen times and only on this trip discovered the play area for the kids tucked in behind the Caro-Seussel.
Same goes for Universal. There are many shows there I usually skip because of my son's disability, yet we have spent many full enjoyable days there.
If you were to literally chart out the times of every single show and ride in either park you would see that even if Scotty were to beam you into the front seat of every attraction with no walking, line waiting, stopping to look at, eat, drink, or buy anything you would be hard pressed to get it all in especially on a day the park closes at 6pm!
Best advice: get a site map at the gate, make a rough plan of what you want to see and do, but be flexible and take the time to relax and enjoy! You can indeed do what you consider "the best of" both parks in one day, but you really would be missing more than you know!
