Relevant notes and citations provided to TED by Laura Vanderkam.
"I recently did a time diary project …"
The results of my time diary project became part of I Know How She Does It: How Successful Women Make the Most of Their Time.
Analyzing 1,001 days in the lives of women with big jobs and families, I found that most were able to combine work and life just fine. The average work week was long but reasonable, clocking in at 44 hours per week. People slept, on average, 54 hours per week, or just a little under 8 hours per day. Subtract 44 hours and 54 hours from the 168 hours in a week, and you get 70 hours left over. Not surprisingly, women found time in those 70 hours to enjoy meaningful relationships with kids, partners and friends, and they pursue their own interests, too. It wasn't always easy, but with some mindful use of time, they made the pieces fit.
"There was once a study comparing people’s estimated workweeks with time diaries …"
See Robinson, et al., "The Overestimated Workweek Revisited," Monthly Labor Review, June 2011
The study's authors found that people who work an average number of hours are relatively good at estimating their workweek -- but, as the estimate rises, the gap between logged time and estimated time grows, hitting 25 hours for those estimating workweeks of 80 or 90 hours or more. While some researchers disagree with this finding, I know from my own time diary studies that people often have a vision of a "typical" week that does not involve late starts, family issues, dental visits or anything else that might detract from regular hours.
I used to think I worked 50 hours per week. Then I logged my time for a year and found my average was a lot closer to 40 hours. See "The Busy Person’s Lies" from the New York Times, May 13, 2016