I wake up at 5 in the morning and I am usually in to work by 6:30 because I have a half hour commute. I think work until about 3:30 or 4:00 and start my half hour drive home. If it is a day that we have a board meeting, those don't start until 7:00 at night and usually last about an hour.
If we don't have a board meeting and I make it home by 4:00 or 4:30, I am usually still checking my emails and replying to service requests via email through the night. Occasionally my boss will call me and need something late at night. I am pretty much on call 24/7.
In addition to working my main job, as many others have mentioned, I am also on Steemit pretty much all day. I keep a window open at my desktop that allows me to post, comment, and vote throughout the day.
If you wanted a hard number I would say on most days I work 9 hours, but the reality is actually much more of a gray area than that fixed number.