My unprofessional opinion (what I would advise my own kids) on the overall question: should I submit an art sample?
If what they are imagining in their heads as your level based upon the written description is lower than what your work sample would be, then definitely submit.
For example, if you have had the lead in the school musical, they are imagining a pretty good singer. If you are truly AMAZING, then absolutely you need to submit. If you are just “good for a high schooler,” then I would let it stand without submission.
Bottom line: if the submission will result in someone saying “wow” then submit. If not, then don’t.