It means that for a long time people have called it 120% time because most of the people who still 'used' their 20% time were working 120% the amount of people

It means that for a long time people have called it 120% time because most of the people who still 'used' their 20% time were working 120% the amount of people that didn't use their 20% time. Despite Google not really stack ranking, it's kind of like inflation. If you work 40 hours a week and 20% of the time, you work on your 20% project, you look 20% worse than the average 40 hour a week worker that doesn't use their 20% time.