The real lesson of Jaws was that if you market a film well and make sure that it’s on thousands of screens, you can be reasonably assured of a big opening. The marketing blitz and the wide release work on the opening weekend because they’re a form of what economists call signaling. A movie that hasn’t opened yet is a classic example of an ‘experience good’. You can’t tell if it’s worth seeing without seeing it, you you look for early signals, which Hollywood is happy to provide: a clever trailer, a big ad budget, a wide release. You’re supposed to think that a studio wouldn’t spend so much or put a film on so many screens unless it was confident that it could recoup it’s investment, and therefore the movie must be worth your ten bucks. Signalling though, works only as long as the experience good has not been experienced. Once people start talking and reviewers get griping, the ads don’t much matter. That’s why studios spend almost their entire marketing budgets before a movie opens.