Pixar and Strategy
Roger Martin in his book The Design of Business discusses how business should operate on both reliability and validity. Reliable processes are guaranteed results (as long as the assumptions they are based on do not change). Validity needs to be proven and is risky, but can open new opportunities that reliability cannot.
Animated movies cost a lot of money to make, and marketing new IP means starting all over again (ever seen a movie poster with the phrase - From the makers of…). Sequels are much easier to market, people are already familiar with the film and characters, so once you have made a good new movie, you are pretty much guaranteed a similar level of box office with a sequel (if not more).
After Pixar’s initial string of original hits they settled for a rhythm of new stories, and a rhythm of sequels. This is a mix of reliability (sequels) and validity (new films). If a film does not do well at the box office this leads to a lot of wasted capital, so sequels offer a way to offset the risk of new films - whilst ensuring that new films are made (which will generate the new sequels in future).
Citations: