One day is generally enough for Universal Studios Hollywood due to its more compact footprint and fewer total attractions compared to its Florida counterpart. However, for Universal Orlando Resort, one day is typically insufficient to see everything. The Orlando property consists of three distinct theme parks: Universal Studios Florida, Islands of Adventure, and the newly opened Epic Universe. Even with a "Park-to-Park" ticket, you would only be able to hit the major "headliners" (like VelociCoaster or Rise of the Gru) across two parks in a single day, likely skipping most shows and smaller rides. To fully experience the immersive lands of Harry Potter and the new worlds of Epic Universe without rushing, a minimum of three days is recommended for Orlando.