It really depends on the state of the screen. It's easier with reading PDFs, for instance, when you can get away with a full refresh on page turns.
Versus someone drawing on the screen with a lot of zooming and panning. People with the tablet would notice that when they stop a series of these actions that were back to back, the screen will "clean" itself after about 5 seconds of idleness.
Versus someone drawing on the screen with a lot of zooming and panning. People with the tablet would notice that when they stop a series of these actions that were back to back, the screen will "clean" itself after about 5 seconds of idleness.