Ha ha ha ha! If I'd defined "success" as "average views", I'd have declared failure long ago.
Seriously though, as Dennis said, it really is a personal thing. My definition of "success" was to have people actually talk about my serial. To me, or other people. That's mostly why I stopped! After over two years, no one had found personified math engaging. No remarks from relatives, or coworkers, and it was the same two people making very occasional comments. As far as "average views" went, it was under 50 per post (posting twice per week), which was fine, but for months that wasn't improving at all either. Hence switching blogs, and trying a new genre.
On the new site, posting every week, without fail, since September, I don't top 20 views in a day (with some exceptions around Apr 1st). My math archives are actually seeing more hits, so I'm toying with returning and running two serials in tandem. The other thing to consider is that I think my writing is improving. So that's a success. I've also never made any money (granted, I've never tried).