I took Wednesdays off for about 5 months once to burn PTO (the accrual policy was changing, and I would have been over the cap at the end of the year). That wasn't systemic, most of my colleagues either took more vacations before the change or planned to take some bigger blocks.

It was nice to have a day off in the middle of the week, although I had some occasional meetings, I needed to take, which was bleh. It was also super easy to schedule interviews when I was recruited by a former coworker. Unfortunately, I didn't end up fully using my FMLA newborn leave, because it needed to be used in week long chunks and I had planned to burn PTO first, and use the FMLA weeks later, but I switched jobs instead (and went back to a 5 day week)