[Bells]

Well, seeing as this is a forum, there are plenty of members of different ages. As a result, people can be online at any time depending upon when they are free and their working or school hours. Not every adult works 9-5 on weekdays - working hours vary, so I guess it gives them different free times.

And for students at school/college, they obviously don't go on weekends, and then they may have holidays etc. or may feel ill so take a day off! That's why you'll find at least one member online at any given time, really. And it gives them the opportunity to watch TV programmes etc. as well if they choose to.