Personally, I think requiring a specific number of words in a communication can be a mistake. I am thinking of those sorts of assignments when a teacher requires 500 words on a topic. One of my very favorite books about writing and education is "Uptaught" by Ken Macrorie. It is not an easy book to find these days but it is worthwhile. Right in the beginning, this experienced teacher of writing and English quotes from student essays that show a tendency toward more words instead of less and bigger words instead of straightforward language, tendencies learned in our schools where such strategies often lead to higher grades in language.
One of the things I have admired about Twitter, even though I have not visited the site yet or joined the several hundred million (!!!!) users is that posts (tweets) are limited to 140 characters. I find that nearly anyone equipped to speak English (knows the language, can see and think and speak or write) has interesting things to communicate, unless they are forced to pad their actual comments with stuffing designed to meet some artificial length requirement.
I am confident that teachers could cut their reading and marking load by requiring a severally limited communication for most assignments. One word might be a good required length, with extra points for a very clever or apt word used.
I admire Michael Pollan's Food Rules for its brevity. I admire a good poem for the same reason. A good joke or folk saying or proverb or rule of thumb underlines the value of a few well-chosen words.