Depends
I spend too much time online **, but not all the time at JT. Have no idea how many hours though. I think I might track my online time for a week or so, just to get an idea . Usually I pay JT a lot of short visits on one day, if I have access to the internet. But sure thing is that if I'm at home, I am online. Most of the time doing stuff in the background like AnnU said.
That's the case when I've got a lot of time, like the past week(s). But now a more busy time kicks in for me, so I guess my online-time will reduced by 50%. It should be anyway... but I know myself & probably it will only be reduced by just a few minutes

** But I'm not an addict :P