If people think 1 month is too short a time frame, should we do every 3 months, with the due date being the month after each recital? That would mean only 4 pieces per year, and if we rotate genres, it means each genre only happens about once a year.
Also: Whatever time frame we decide, I don't think the "deadline" needs to be strict. At r/piano, we allowed submissions up to 3 months late. So if we make this first event's deadline the end of June, submissions are accepted until the end of September (and maybe beyond that, because who's really going to keep track).