These are the thoretical best possible times for each grain category (on the website that is). 100 grains is 24.6, 1,000 grains is 3:59.9, and 10,000 grains is 39:30.9. I'll update this when I can get each time to a thousandth of a second and get frame perfect answers. 39:30.9 for 10,000 is probably unacheivable for humans, seeing as that would require 1000 frame perfect inputs, but 24.6 for 100 is definitely doable and 3:59.9 for 1000 may be acheivable. Note that this also requires perfect luck for just guessing the answers and pressing the answer frame perfectly.