Applying to Top 20 Schools Based on GMAT Score Alone

First of all, no. A great GMAT alone will not get you an interview. Most schools talk about a holistic application process so they review everything you submit and take it into consideration.

Secondly, and this is school specific, your application will typically reach the admissions desk. Some schools utilise student reachers but for some other schools, each file is reviewed by a member of the admissions team regardless of whether it is good or bad.

I personally think GMAT helps to a point. It needs to be competitive enough so that you are in range for the school but all it does is put you into the "GMAT is in range" group of people. After that the rest of your application comes into play. Having a superior GMAT obviously jumps out and will be a plus. But a 800 GMAT will not offset a lack of work experience, low GPA, or zero community engagement. Do a quick search for Low GPA applicants though. I know there is a fantastic thread about doing your best to offset and explain the circumstance as well as success stories for people who have got into great schools with low GPA.