Sometimes this works and sometimes it doesn't. Way back when I worked for Big Oil, I was the nearly the only geophysicist working on the (company approved) 7:00 AM to 3:30 PM flex schedule. What this meant was that I could get one set of jobs through the mainframe before the rest of the crew showed up at 9:00. Then I could get a second pass through along with everyone else to look at in the early afternoon and submit a 3rd before I went home at 3:30. The 9:00 crew could only one run completed and a second submitted before they went home at 5:30. In other words, I got 50% more work done than the rest of them. However, during one performance review it was noted that by not being at the office until 5:30 I was hurting my chances for advancement. Apparently, at this company, face time trumped productivity.