Depends on your definition of back side of the clock.

If you fly Z and do intra-Europe, some people try to stay on their normal body clock. If you land at 6am, it may only be midnight or earlier at home.

Asia is basically 12 hours different so if you fly at 10pm, that's 10am on your clock.

If you're talking strictly day/night local, then Z is pretty much all nights. The MD flies a lot of daylight internationally.