Marvel and DC Comics have been opting for shorter runs, but longer runs from creative teams are vastly superior.
Marvel and DC Comics are the most prolific superhero publishers, with their popularity stemming from both their characters and the creators who worked on the books, including Jack Kirby, Gardner Fox, and Stan Lee.
These creators defined and re-defined characters in long runs, helping to push superheroes forward, with notable examples including Kirby and Lee's 108-issue run on Fantastic Four.
Once upon a time, as long as a book was successful, the creators would stay on it for as long as possible.
Author's summary: Longer comic runs make better stories.