>>bmitc+(OP)
My impression is that people don't measure the time they work, but judge it by their impression. First, they think that they work for, let's say, 40 hours per week. They don't consider how much meals, coffee breaks, mental breaks, off-topic office discussions, checking social media, visiting restroom take. Second, when they work overtime, they get tired and overestimate the amount of time they worked. 10 hours of overtime probably feels like 20 hours.
100 hours is equal to 2 full-time jobs and a half time. People believing that number should consider how they would live going to their second job after their day ends (second full-time job) and working on weekends as well (half-time one).
Under ideal conditions, someone might be doing it. But, people shouldn't be throwing around these numbers without any time-tracking evidence.