I read that subtitle 3 times and it still doesn't make sense. Is my coffee bad or has the editor slipped? Probably and extra “if” after the “But”? “But if the

I read that subtitle 3 times and it still doesn't make sense. Is my coffee bad or has the editor slipped? Probably and extra “if” after the “But”? “But if the tests work much better when taken three times over the course of several days.”