More than 80% of working moms utilise this option and around 10% of dads. [1] Among my friends I have parents where both of them work 4 days, taking the 5th day off on separate days, and their kid goes to daycare 3 days a week.
Note that most government subsidies (for childcare) are set up to encourage working at least 32 hours per day.
[1] https://money.cnn.com/gallery/news/economy/2013/07/10/worlds...