I think that the spirit of the advice is apt, but that the letter of the advice is not.
Sometimes, "keep writing" is what kills a story for me. Plunging headlong into the unknown middle of an idea without firm enough footing. It is a foolish man who built his house upon the sand.
I think you should practice writing everday, but heck, journals can work for that if you're in a planning stage in your novel. You should also keep doing writing tasks, like asking those ever-important questions and outlining, but just "keep writing" seems to be a recipe for disaster.
Thus the invention of the revision 14 site. Oddly enough, after I started to put it together, and started getting articles and such for the site, my writing came much more naturally, not to say that its any better, but i hope it is
Writing seems to inspire writing, though I would never keep writing on the thing that was blocked..
so maybe its just the process of opening your mind....
Write always means literally write everyday. Set a goal and write that amount of words every single day even if they are crap.
This way your train t he creative part of the brain to come out when you sit in the chair at your alloted time. Like any habit it takes 6 to 8 weeks to develop fully. Once you do get in the groove of sitting in your chair at X time a day (my main time is 10 pm to midnight) the creativity will come and writer's block will come less often.
I forget who said it first but: The only writers who get writer's block are those who have another form of support.
In other words write like your next meal was dependent on this written work.
Shawn
-- and the great thing is, i enjoy it MUCH more, get A LOT more done, and it reads A LOT BETTER ... !of course, saying this i well accept that i have not entered the professional market, so my words come with a grain of salt...
Let me put it this way....I am working on my first murder mystery right now. It's a tough type of thing to write. I wrote and wrote every day like I was supposed to until one day I realized I had skipped evidence, testimony, and important interviews. Any one of these things alone I could have just made a note of and kept going. People told me "keep writing, don't look back!" but how could I keep writing when half the stuff I wanted to refer back to never happened in my version of events?
So I did keep writing. I went right back to the beginning and started over, with a crisper outline and a more detailed description of when I had to plant clues and red herrings. It's working much better, but not for the "keep writing" advice.
Well. I write in a journal (story and otherwise, jumbled into one. You should try it, if you don't. It's very therapeutic. And free!), and I'm working on a novel, a comic book miniseries(*shrug* 
), and several short stories. So I write. And write, and write, and write.
It's good. Sometimes, like cgamble has said, the words flow like wine, but othertimes, they flow like frozen wine.
So I don't write. Is that terrible of me, as a writer? That I can go days without writing a single creative word?
I don't think so, because while I'm not writing anything new, I'm editing the old stuff, going through the novel, the comics, and the shorts with a fine-toothed comb, making sure that there are no spelling errors or inconsistancies (because that's the reach of my editorial skills, remember...).
So, after a long, revealing, and somewhat useless rant, I've come to this conclusion: A writer should keep writing (Billy Crystal's Throw Momma From The Train character's motto comes to mind: "A writer writes. Always"), but it doesn't have to be new.
Just my opinion,
Cristian V. Gurau
PS--am I the only one who thinks that the window below the posting space is too small? Is that just me?
[This message has been edited by cvgurau (edited June 25, 2004).]
But I believe, as has been said above, that writing SOMETHING every day is crucial, simply for self-training purposes or to keep the mind exercised. Journals, writing exercises (which can often turn into the roots of story ideas), poems, even clever posts on Hatrack.
If the block is lack of confidence or fear of failure or something other than a structural problem with the WIP, and the writer skips to another project or journal or whatever, he'll merely join the legions of would-be writers who never finish anything and can't figure out why.
Having others critique a blocked work may help. Feedback is essential. Even if it's bad, the fact that someone took the work seriously gives it a legitimacy the writer may need. I'll go out on a limb and say that writers who hobnob with other writers -- in critique groups, conferences, classes -- have a greater likelihood of finishing and publishing than those who don't. (Another 'Duh!' moment, brought to you by Kolona. )