Here's a realistic scenario...
You get a call from your agent that you have an audition and you need to use an accent listed in your Special Skills. Perhaps it's been a while since you've used it, so why not visit here for a quick brush up:
The International Dialects of English Archive (I.D.E.A.)
http://web.ku.edu/idea/

All recordings are in English, are of native speakers, and include both English language dialects and English spoken in the accents of other languages.
http://web.ku.edu/idea/

The archive provides:
downloadable recordings of accent/dialect speakers from the region you select text files giving the speakers' biographical details scholarly commentary and analysis in some cases and, in most cases, an orthographic transcription of the speakers' unscripted speech This cool service was developed by Paul Meier, the author of the best-selling dialect
textbook, 'Accents and Dialects for Stage and Screen'.
http://web.ku.edu/idea/