Novel or Short stories?

That is the question on my mind right now.

My current project is Maidens Song; The first in a planned series of books following the life of the immortal Joseph Hunter. So far it's going well. There have been the normal dry spells of course, when I tend to over think a relatively unimportant part and end up frustrated at myself. Over the course of the past week I have been carefully reviewing what I have so far. And as pleased as I am in the most part I know there are a lot of changes to be made. I also noticed how my style changed and improved the further into the story I have so far. This got me thinking: "Should I spend some time working my short story ideas and use those to hone my writing skills?"

Right now with current time constraints (my full time job as a UNIX Admin + being back in school working on another degree) it seems that the short story option would be good. Or do I just go ahead and do both? After all who needs sleep.