Frank #2 has the right idea, if what you’re looking for is how to look most productive.
If you’re looking to be more productive, flextime is the way to go. Everybody has peak hours of efficiency.
If your type of business involves contacting people from outside agencies, you’re best to stick with the core business hours (probably 9-5ish). Of course time zones are a factor here. I’m on EST, have been here since 6am, and can’t really get a lot of work done until the customers on PST are in their office.
Ya you normally get dirty looks when leaving early by everyone else. I’m out the door no later that 12:00pm of course I come in around 3:30am to 4:00am. Love being here a few hours by my self. Our company has office all over the U.S and two in Canada. But all the servers are in this office so it much easier to work on them when no ones around. But it really depends on you and when you can get the most done. The guy that comes in to cover the afternoon hates the morning shift just as much as I hate the afternoon one.