The last time I was in an office they had “core hours” from 10-2, which is when everybody had to be there in case of an all hands and to make scheduling meetings easier. That way you’d have some folks come in as early as 7 and as late as 10, and leave as early as 3 or as late as 6.

Of course, this was back when Skype was the only option for videoconferencing so it made sense.