Same thing happened with Full Marks last year. All throughout summer, multiplayer events were continuously triggered week after week. It's because Jam City's target demographic (children) are out of school for summer vacation. They're glued to their iPads and phones because their parents don't know how to raise them, so they're more likely to spend mommy & daddy's hard earned cash on microtransactions to ensure they win the events.
Come back in September when the kids are back in school. The multiplayer events will go back to popping up once every month or two. I'm not kidding. For your own sanity, you're better off just pretending this game doesn't exist until the first day of autumn.