Although I most often have a HubPages wndow lurking, no matter what else I'm doing online (or off, for that matter), weeks can go by without my writing any new Hubs. Days can go by without my reading any Hubs. I leave the open window lurking on the screen in case I have a few minutes and want to take a mental break from something else I'm working on, and then I'll go look for something new on the forums (or the Answers section, these days). Both can give me ideas for writing (on here or elsewhere). Both make good in-between time breaks. Both can sometimes offer a "mini mental challenge" to get my mind away from more demanding (or else boring) work (or waiting) that I'm doing.
Sometimes, though, if I don't have a lot of "real" work going on and start thinking up a bunch of things I may want to write about, and/or if I'm in an "I-need-a-do-nothing-day" mode, I'll disgust myself by frittering away the occasional (but rare) day on here while I either let the writing subjects incubate in my mind as I otherwise waste time on here, waiting for whatever it is I'm incubating to hatch. Something else I do (separate from "real" work) is be on here, frittering away time; while I'm also writing other stuff "for myself" that isn't ever going to be a Hub.
So for me, there's really no clear-cut "being on here" much of the time, and there really aren't any average days.
Having said all that, I'm kind of horrified to realize that (with a lot of rain and not too much work to do in the last several days) I've pretty much done nothing but fritter away time on useless stuff on here a good part of this week. It hasn't all been a waste, though. I've gotten quite a bit of writing-for-myself done in the meantime. Some of it may get turned into Hubs. (For someone who is so great having "A System" when she's doing work for other people, I sure seem to be system-challenged when it comes to my extra-time efforts.) It all works out. Next week I may disappear from here for several days. (I guess I kind of "bank" my time on here, rather than really invest it.)