tl;dr: Borrowing Wayland's "every frame is perfect" goal, the author argues UI quality should be judged by whether a screenshot at any moment makes sense—no white flashes, partial loads, relayouts, or inconsistent state. Animations are a common failure point: examples from Safari, Photos, YouTube, and Preview show janky in-between frames, desynchronized components, and nonsensical transitions that erode user trust. The takeaway: designers and developers should scrutinize not just start and end states, but every frame between them.