So there is an inevitable trade-off between writing short stories and writing novels. Which might not be too bad, given that it's obviously impossible to support more than your writing habit on writing short stories nowadays, and frequently enough not even that.
On the other hand, novels are no guarantee of selling either, and they take longer. A lot longer, if you write like me. And there are short markets. Especially anthologies, which tend to be interesting because they also tend to be fleeting. And more novel-work you do, the more likely it is that you would have to conjure up a story idea to fit it. And then write it in time. And then go out and compete with all the other stories in the slushpiles, because every theme anthology makes its presence known there. (Was in an online discussion about an anthology on dirigibles, and someone observed that slush piles would be floating for a while until the magazines had bounced them all.)