The thing is, Eink's waveform is kind of secret afaik, everyone has different tuning.
We had some secret eink sauce (propriety waveforms) to get the high refresh rates and colour contrast without a full flashing screen reset, but even then you need to run longer maintenance refreshes occasionally.
Pixels are just vertical columns of viscous fluid with charged ink particles. A waveform is just voltage changes over time to these columns to shift the particles up and down. More black to the top = darker shade of grey. Colour (in the gallery display, at least) is the same, just with each CMY particle group having different charges and responses to different waveforms.
Every once in awhile this vertical column gets messy with loose particles distributed through it (ghosting, muddy contrast) so performing a hard rail-to-rail voltage reset forces all the particles up and then down, and gives you a clean slate.
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.
> Image update time - 25 ºC - - 4 - sec
I'm guessing you could probably push that somewhat by going beyond the specifications, would wager a guess how far though.