Based on my Hubs (I can't answer for others), it's normal to have an initial "bump" in traffic for a few days after hitting Publish. Then the traffic will naturally fall off (often to zero in my case) UNLESS the search engines decide they really, really like what I've done.
Some writers (from what I read on HubPages) are pretty consistently able to produce Hubs that have staying power and get steady traffic for years. Others never get the knack at all. I'm somewhere in the middle, with maybe one in ten (on average) "getting legs" and producing 24/7, 365.
The odd thing for me is that I've never been able to predict exactly which Hubs will catch fire and which won't. I do know that certain categories have better chances; my How To and Product Review titles have some real winners.
Being patient does help. For example, one of the strongest Hubs I've got, chronicling my wife's arduous journey in getting Clear Choice dental implants, was up and running for about six months before it suddenly "took hold".