When I started writing I tried to stay focused on one project at a time, which seemed like a good strategy to see the manuscript to completion and get it published as soon as possible! But there are downsides to focusing on one story at a time.

The one project method can mean long periods  of just editing.  I mean I love editing as much as the next writer, but a writer cannot live on editing alone.   Having multiple projects lets you work on whatever interests you the most that day - writing, researching, twittering, or even editing.

Focus can mean lots of waiting - waiting for feedback from your critique group or a response from an editor.   Multiple projects let you be productive and keep flexing your writing muscles.

Though it sounds backwards, focus can be inefficient.  If you research publishers with just one manuscript in mind, then you need to complete the research again for the next story.  If you have a few at hand you may note a good editorial fit for each one during your research.

This is your brain on writing...
(brain by Rodrigo Galindo via sxc.hu)
Having multiple projects going creates an "idea web" in your brain which catches juicy tidbits around you.   You see someone get tripped by a dog leash and fall into doggy poo.  Aha! Perfect for your dog walking service book.   Your kid orders five flavors of ice cream and the dopey teenager behind the counter actually puts five scoops on one cone which is now larger than your child.  Voila!  Great for your magic candy shop story. 

Finally, sometimes you just don't have a choice.  You try to focus, but your muse becomes a college roommate on Thursday night convincing you to go out for one drink even though you have never successfully executed the one drink strategy.  Ever. 

Let's just jot down this one idea, your muse entices.  While we're here, how about a few sentences?   Then a whole story spills right out of your fingertips.  And sometimes that new idea is more exciting than the other.  It's not that your first idea stinks (though that's certainly possible), it's that you are fatigued with it.  You need a little distance in the relationship so your heart can grow fonder. 

The main downside of the multiple project approach is your brain feeling like a cave of fluttering bats about to explode - but hey, everything has side effects.

What's your approach?