Hunter, I think your observations are correct.
I, however, am an amateur author and a stay at home parent. So when I am not involved with my kids, or writing my next book, I am searching out new material or ideas or browsing the forums and threads here.
Its Christmas time so I expect the posting times will vary a lot but I tend to come on either morning or night as well so good perception on your part. I think weekends are slow because its weekend! lol So much to do that you can't get done during the week.
Sometimes its early in the morning or late in the evening it really depends on my schedule for the day. So when I do get online I try to make it one shot and answer every thread my character is in and a couple of general topics if they peak my interest.
I have noticed that most people do post in the morning or evening, but with this being an international board that actually spreads the posts out a bit throughout the day. Between the evening when I check and the early morning when I check, usually very little has changed, but I get emails about mid-morning through lunch about a lot of updates. I imagine this is morning to most of the people I game with, but not for me. I am on all day and just post whenver I need a minute to take a break from my work.