I vote for percentages on behalf of all the semi-autistic males out there. We like to watch progress bars on software installations – even better on disk defragmentation.
We like percentages on the bars because we can calculate how much time is left as a multiple of how much time has passed. See how quickly it drops from 8 times to 7 times to 6 times... And if that gets boring as the fractions get further apart you can reset the clock at 50% and start calculating how much time is left as a multiple of the time that has passed since you got to 50%. Or you can calculate the rate of progress you need to finish the book by 10 o’clock and then you can calculate how far you are ahead/behind schedule and translate that into minutes. And then you can...
Oh. Right. I’ll go and take the pills.