There's a tendency sometimes to leave certain words implicit. "It does not [even] take 21 days to form a habit." Some of those linguistic habits never leave the

There's a tendency sometimes to leave certain words implicit. "It does not [even] take 21 days to form a habit." Some of those linguistic habits never leave their birthplace, giving you colloquialisms like "do you want to come with [us]" in the Midwest. Most don't have any regional association though, and sentences with dropped fragments sound perfectly normal, with your mind filling in the gaps. In this case, the sentence is correct (though ambiguous) as written, but it has the same words you often see from a longer phrase with an omitted word implied through tone and other vocal cues, a pattern used commonly enough that I'd wager most people interpret it the same as you.