The flip side to this is knowing when to bow out gracefully like a poker player who's luck has run out. Producers can go too far and water down a series if not reeled in. Some notable examples are Friday the 13th, Rocky, the original Batman movies dating back to the '80's starring Michael Keaton and Superman starring Christopher Reeves. I enjoyed the first movie or two in all of these but quickly lost interest afterwards. The plots grew weaker and actors more comical in their roles.
Finally we have the sensible directors who know when to pull the plug after a bad showing or two. Case in point the current Spiderman starring Andrew Garfield (really hope they kill this series) and Fantastic Four which aired years back starring Chris Evans and the lovely Jessica Alba. Hey quick trivia.... did you know Chis Evans is the first actor to portray 2 different Superheroes with simultaneous movies out? He's the Human Torch in the original Fantastic Four movies and Captain America in said title and The Avengers. Apparently Hollywood frowns on actors having multiple roles regarding this genre, they believe it confuses the public.
I've been a comic book geek since I was old enough to read and know the background of nearly every hero and curious to see how they pull this new Fantastic Four off? The original story line was Johnny Storm (Human Torch) and Sue Richards were brother and sister but in this movie Johnny is portrayed by a black male. Intriguing indeed and I'll be first in line when this movie premiers. Flame on!