We did a walk-in for dessert at Prime Time a couple years back and had great, friendly, prompt service. As for ADRs, we asked specifically about this a couple months ago because we wanted to eat at both Marrakesh and Sci-Fi for dessert only. We asked did we need an ADR just for dessert, and the answer was "You're not even going to get in the restaurants even for dessert without one. You HAVE to make a reservation because the number of people eating at TS restaurants increased by a lot in the last year or so and walk-ups aren't accepted hardly ever." Actually no, she said walk-ups were never accepted. Same story from 2 other CMs when we called back to ask some other questions about closing times, and cancellation policies for California Grill. They were the 2 who said walk-ups were rare. So make those ressies if you want to guarantee yourself a chance to eat anywhere.