The correct solution - which will never happen - is simply to abolish public screwels.
How about people just having the intelligence to realize that a Valedictorian speech should be about 5 minutes - start out with a joke, mention a quote by JFK or MLK, try hard to apply the quote to high school, some mishmash about one chapter ending and another beginning, thank the teachers and parents, congratulate your peers, and just keep the show moving on a hot June day so people can get on with the post-ceremony fun.
As bad and as cliched as that rough outline is, it's far preferable to am obnoxious pest who got the idea that her tippy top grades somehow make the Valedictorian speech all about her.