This is a good thing to say to film students. If there's a story point that you don't feel right about, that there's a question you have - "Does it really make sense?" Or, "Is that plausible? Is it implausible? Is it set up?" Or whatever. Go at it. Don't let it go. If there's a question in your mind, you're probably right. You probably do need to work on it and think about it more.