I believe that a writer learns from every story he writes, and when you try different things, you learn different lessons. Working with other writers, as in Hollywood or in a shared world series, will also strengthen your skills, by exposing you to new ways of seeing the work, and different approaches to certain creative challenges.
George R. R. MartinA craven can be as brave as any man, when there is nothing to fear. And we all do our duty, when there is no cost to it. How easy it seems then, to walk the path of honor. Yet soon or late in every man's life comes a day when it is not easy, a day when he must choose. (Maester Aemon)
George R. R. Martin