It is easier to find an alibi,  you are expected to be at work from 9 am to 6 pm and have a "Dr Appointment" or "Take Lunch" in between.

Past 6 PM, what is the excuse?

appointments is the fact that they post the message on the same night they are looking for the appt. You can't post something at 9 or 10 at night and expect to get many takers!

I travel to DC for business so evenings are the only free time I have. When I have a frw hours available in the afternoon I usually go for a nice massage+ if I can book a last minute appointment.

With my work schedule, navigating around northern VA and DC, and my SO to consider, I'll try to schedule anywhere between 11am and 3pm. I can get around town without worrying about rush hour traffic, and I have enough time to get home and clean up. It kinda sucks because I've had my eye on a couple local providers but they're never available before 6pm due to other personal commitments.

I'd bet the late night requests on here are more from last-minute decisions out of boredom or impulse, though I'm sure plenty of guys prefer scheduling evening appointments.

I am a morning person. Morning fun is very good.
Some ladies are not AM people, so sometimes it's an afternoon appt.

Early mornings as long as...

...my accomplice is a morning person as well.  It is also when I have the most control over my time."Client breakfasts" are always great and i can usually get to the office by 9 or so.  One of my favorites admits she's just not functional before 10am, so we have a "client lunch".  However, when traveling, evenings or very late afternoon meetings are required.

I prefer mornings.  I like to make sure I'm the first appointment of the day (hopefully)