For those that know already a lot, and just need that extra thing.
For those that wouldn't have time for anything more, better 'short & now' than 'maybe-never'.
For beginners who don't feel like committing to a diploma course yet: a taster of what it would be like, and in the meantime getting started with music, no pressures.
For an excuse to visit London and call it a business trip.
For a gift to someone that is passionate about music but needs some encouragement.
For your work, for extra skills, for inspiration, for fun.