The body of your personal statement is going to be hard work _ you need to use around 50% of your word limit to give the admission representatives concrete evidence of why you stand out from the crowd in this application process. The body is also where you will be answering questions and giving examples of experience and affects of experience. Answers and evidence need to keep reflecting who YOU really are. If you're struggling to keep under the word limit, allocate each question a word limit as well.
If you are applying to several different schools using one generic statement will be easily recognized and just as easily dismissed. WHY _ because you will be seen as not making an effort sell yourself to this particular school, low effort equals low interest to admissions representatives. Remember the admission committee will likely view thousands of these statements from qualified candidates and they will spot a weakness, flaw or lack of attention to the process in a heartbeat. What you don't want to do is give this committee an easy excuse to dismiss your statement and application.