It's tempting to post words as soon as I've written them. But that would be unfair; sometimes I think of a better way to write them the next day, and I'd feel sheepish slinking back to the site to publicly admit that I hadn't expressed myself perfectly the first time.
Also, I don't write a story sequentially from beginning to end. If I have a general sense of the trajectory of the plot, then I'll write up different parts of it. (This lets me skip straight to — or over, depending on my mood — the sex scenes.) I can only imagine how confusing it would be to read unordered snippets — like tearing out the pages from a novel, throwing them in the air, collecting them again, and then reading them.
The Fragments page on my site is a sort of compromise: it's my way of proving that I'm working on something, but I only post the beginning, which should be more or less static.