Three is no longer the fitting number for movie sequels when it comes to maintaining artistic credibility. It's now a matter of how long the studios can keep making money from these sequels because Hollywood is just too addicted to tent poles and the instant stream of revenues they create to be able to maintain any artistic integrity anymore. What comes to mind when I say this is the fact that Shrek, Spiderman, and Pirates of the Carribean are all going to be releasing a fourth installment of their series in movie theaters, despite the fact that despite great starts and sophomore outings, most critics and viewers agree the franchises all sputtered out of gas by the time they hit the back-ends of their trilogies.
What most viewers don't know is that except for the two Star Wars trilogies (the prequels and the originals), Shrek, Pirates of the Carribean and Spiderman have been the three biggest trilogies ever to hit the box office, boasting a combined four films in the top 10 highest-grossing films of all time and 8 in the top 30, so far. Even when the quality of their films declined heavily in poorly reviewed third installments, they were still able to gross monstrous amounts based on name recognition alone, when viewers set massive opening weekend records in May of 2007 when all three film trilogies came out. Before anyone qeven had time to tell their coworkers when they got back to work on Monday, just how bad the films were, these films made their money back in three days, and that's likely what will happen when the franchises come back again in part IV, until people wisen up and break their moviegoing habits.
Even worse in this trend is that studios can't afford to give their star properties much breathing room anymore. Look at The Incredible Hulk, Star Trek, James Bond, Batman and the previously mentioned Pirates of the Carribean in comparison to Star Wars and Indiana Jones.
Indiana Jones and Star Wars were films that essentially stopped after their stories were done being told. Due to fan demand and an appropriately long enough hiatus, these two franchises came back 16 years later in the case of Star Wars and 19 years later in the case of Indiana Jones. Part of the justification was that the stories could be introduced to a new generation. Although neither one of these franchises were particularly good when they were rebooted, one can't deny that the hype, anticipation, and ultimately, their opening weekend grosses, were far greater than that of any of the films in the first category.
In the first category of films, there was virtually no time to wait until a generation had passed. Hollywood tides move much faster than they used to and no one can afford to wait 15 or more years to not capitalize on a hot property of theirs. Thus we have:
-James Bond rebooted after a measly four years (Die Another Day 2002-Casino Royale 2006)
-Star Trek reappearing in theaters after only a 7 year break (Nemesis, 2002) and a 4-year break since the Star Trek franchise dissapeared on TV (Enterprise in 2005)
-Batman taking only a seven year break between Batman and Robin (1999) one of the decade's biggest failures and Batman Begins
-Hulk rebooting after only a five-year break without even pretending to be any sort of sequel or prequel. It was simply marketed as a "do over."
-Pirates of the Carribean set to appear only three or four years after Pirates of the Carribean III was lampooned by most critics