Lengthy runs for a creative team on a series isn't necessarily a bad thing, but sometimes even the greatest writers and artists need to move on. Whether it's the fact that they're clearly running out of ideas or that the stories they're telling just feel too familiar and stale, very few creators are immune from this problem. Even J. Michael Straczynski's superb Amazing Spider-Man run ended on a downer with The Other and One More Day. Spider-Man is actually a perfect example of this. Dan Slott helped steer the character through Brand New Day as a new status quo for Peter Parker was formed in the Marvel Universe, and remained in charge of the character from then on. When his stories started becoming more and more uninspired, the controversial Superior Spider-Man came along (which many loved), and he's remained with the series throughout that and Peter's return. There have been several opportunities for him to move on when a significant moment in the character's life has taken place, thereby allowing a new creative team to come in like a breath of fresh air and provide a new take on Spider-Man's adventures. That hasn't happened though, and whether it's Spider-Man, the X-Men, or The Avengers, many of Marvel's titles are dominated by the same writers who simply just outstay their welcome.
