One strategy that I consistently use with all of my MBA, LL.M., MPA, MPP, Ph.D., and other graduate program clients is that I encourage them to initially not worry about word count (or page count, line count, or character count). The reason to write more than the word count is that the best part of the story, the most compelling part, might simply be edited out or never written at all because the writer is too initially focused on a constraint that only applies to a final draft.
While there are people who can write first drafts that are near perfect, most cannot. So it makes little sense to focus initially on word count.
This does not mean that my clients necessarily show me a 2000 word essay when the ultimate essay will need to be 400 words long, but if that is what it takes for them to get a good first draft, it is not a problem. Most really good initial drafts that I read are 10% to 100% over the limit. By good initial draft, I mean one that has within it the potential to become a final draft. Some first drafts are simply so far from what the applicant needs that there chief function is to serve as a basis for brainstorming what will become a good first draft. Some first drafts have a key idea or episode, but are so short that the real story is not coming through at all. Beyond what I might help a client brainstorm, my advice is to always write down anything they think is really useful for the essay.
Once a good draft is in place, through the process of revising word count might go down or go up a bit. As long as the word count is not out of control, say 10% to 30% above what the final version needs to be, I would say not to worry about it until making the final working version. This final version, is, of course, subject to potential revision, but the point is that it is good to be final. After all, writing is never finished, one simply just stops revising.
Word count really is the last consideration. It is part of the final editing process for an entire essay set. While some of my clients are great at editing their own essays, many find that killing their own words is something that they don't like to do, which is why editors exist. My own approach to editing is not to rewrite my client's work, but simply to suggest what needs to be cut and/or what the client should better summarize.
My entire approach is based on the idea that in the end, the critical issues are that the reader believe in the authenticity of the applicant's voice, understand what the applicant's essay, and be excited enough by what they read to either offer an interview or, in the case of graduate programs that don't require an interview, accept the applicant.
I am a graduate admissions consultant based in Tokyo, Japan with clients worldwide. If you would like to arrange an initial consultation, please complete my intake form, which is publicly available on google docs here, and then send your completed form to email@example.com. You can also send me your resume if it is convenient for you. Please don't email me any essays, other admissions consultant's intake forms, your life story, or any long email asking for a written profile assessment. The only profiles I assess are those with people who I offer initial consultations to. See here for why. Please note that initial consultations are not offered when I have reached full capacity or when I determine that I am not a good fit with an applicant.