In the same way deadlines sometimes make us work harder, a word count can help writers with concise word choice.
Last year I participated in a writing exercise with the Throwing Up Words blog. The hardest assignment for me was writing a story in 100 words. Frankly, mine stank. However, I learned a lot from the effort.
I submitted a revised 196 word version, to Utah Children's Writer's 30 Days, 30 Stories project this week.
Here's the link if you'd like to see it.
http://utahchildrenswriters.blogspot.com/ (Thursday, April 18th)
I encourage you to try writing something, perhaps your latest query, taking out 1/3 of the words. Even if you go back and add to it again, as I did with my short fiction, it's worth the effort.