"You Have To Write Every Day"

That’s the most critical piece of writing advice, amiright?  Write every damn day.  If your mother died?  Write at the funeral.  Boyfriend dumped you?  Splash those tears on your keyboard, missy.  Lost both arms in a wrestling match with an alligator?  You can type with your toes!
Just write!  Write!  Write, until you uncork that best-seller from within!
But let’s get serious.  I do write pretty much every day, and I attribute that dedication to the success I’ve had as a fiction writer.  Neil Gaiman once famously told me, “Ferrett, you just need to write,” and after blowing through fifty wretched stories I started to get to some decent ones. I treat my writing career as if my boss were Ebeneezer Scrooge; I show up every day, no vacations, and toil well past the time I’d scheduled.
That’s what works for me, but every writer uses a different method to harness the muse.  Some people must plot in advance; I have to make it up with each sentence.  My friend Kat has to write it all down in longhand; I need a keyboard.  I have to revise a story five times minimum before it’s ready for publication, whereas redrafting for others is like shoveling ashes on top of a burning fire, damping all the energy of that first burst of creativity.
Some people, no, they can’t write every day.  They need to take a week off from fiction to refresh their creativity, wandering and dreaming before returning to the Land Of Difficult Words, and there’s nothing wrong with that. They’re not slackers; this is part of their creative process, and they know this is how they make their best work.
Still, the reason this “Write every day” schtick is so schticky is because every professional writer I know has one talent in common: they write when they don’t really want to.  Because as a writer, while it feels better to write while inspired, most of us soon discover that there’s not much of a difference in terms of what you actually create.  Some of my best writing has come from days where I felt like I was trudging through broken glass, and some of my worst writing has flown effortlessly from my fingertips to land on the page like fresh cat droppings.  For most – not all, but most – what we create has little to do with how we feel about it while creating it.  So most of us learn not to wait for inspiration, but rather to squeeze it out of ourselves like toothpaste from a wrung tube.
You may not write every day, but the world is busy and does not care if you’re a writer.  If you do not make time for the act of creation, then laundry and children and lovers and work will swallow your ambitions whole.  So you need to create time. The more often, the better. Because the number-one enemy that eats talented writers for breakfast, devouring millions of words of beautiful prose that we’ll never get to see, is Real Life.
…And yes, revising stories and critiquing stories all counts for this time.  If you’re thoroughly analyzing fiction, this counts.  You’ve set your brain to work on the big question, which is “How can I make this better?”
Which is the other problem with the “write every day” thinking: it assumes that merely writing is enough.  I know people who churn out 10,000 words every day, and they’re just as terrible when they began.  It’s not enough to just vomit words onto the screen – it has to be a focused writing, thinking about the details, bolstering your strengths, asking, “How can I do this better?” If you’re endlessly enamored of your own work, convinced it’s beautiful and not a word could be improved, you’re not writing, you’re masturbating.  And there is absolutely nothing wrong with masturbation, but it’s not improving anything except your ability to pleasure yourself.
When you sit down to write, do so in a focused manner.  Think, “How am I going to make this the best story in the damn world?”  You probably won’t, but asking the question and analyzing will lead you to better and better techniques.  And one day – even if that’s a day you did not necessarily write – you’ll find that you’ve become the sort of writer you’d hoped to be.
Good luck.