You will have to ask Hub Pages. I have been around almost three years. I wrote my first hub, and it was published. Then for a variety of reasons I did not write any more for several months. When I did each was published.
I know a lot of writing sites are demanding more samples of your work, but those are mainly the content mills, where you write for an unknown clients so they can publish your work under another name. There is good money to be made, but you do not get to retain the work.