The animation itself is rather simple, whether using the built-in preset or making it yourself: a Range Selector goes from Start 0% End 0% to Start 0% End 100%, Opacity for this animator is set to 0% and Random order turned on. But the result is not a slow, smooth fade, where the eye can actually see each character fading out over time. What I get is almost an instant disappearance of the characters, one at a time. The fading animations literally take only two frames each! The only way to see them is to manually move on the timeline one frame at the time.
Moving the Range Selector's keyframes up and down the timeline only determines when does the whole thing start but doesn't influence the speed of the actual single characters fading.