Piter
Some schools have 400 or 500 word limits on essays. Sometimes it can be ridiculousness and just impossible to put all in 500 words. So, do you exceed word limits? If so, on how many words?
This issue is much-discussed every year.
Most applicants find that word limits actually help them write stronger essays. You are forced to make tough choices and really separate the wheat from the chaf, so to speak.
As far as going over goes, it's pretty rare that anyone's actually going to count the number of words you have. Within a certain margin, anyone who's not counting words won't notice that you're under or over -- most folks say 10% is completely normal.
If you choose to go over more than that, you risk a lot:
* You can't follow directions
* You think that rules don't apply to you
* You have an unfair advantage over those who did maintain the limits
And even if the adcom doesn't think the above, they are likely to hold those extra words to a high standard. In other words, those extra words better be earth-shattering and worth their time.
You hear stories about people writing more (I mean much more, not just another 10% or something) and still getting in. But it's a risk, and one that I wasn't willing to take.