I do believe there are merits to both and, ultimately, it's whatever the writer finds most interesting/convenient/important to them. Some people think it is lazy to reuse a character, but others find it too bothersome to invest in character creation when writing isn't guaranteed.

For me, it is whatever I feel currently suits the situation I am in. I have some characters who I just [i]adore[/i] writing and I would rather tweak them to fit a setting than create a new character who just might not enjoy writing in the long run. On the other hand, character creation is fun and different settings allow me to create a diverse range of characters that I might not otherwise have devised had I simply been reusing.

Writing is creative and the same way that I would have no qualms about redrawing a piece of artwork with a different composition, I have no worries about rewriting characters. Some characters are kind of in between 'reuse' and 'one and gone'; I pour love and soul into creating them only for the roleplay to never take off the ground; these characters, if I am invested in their design enough and want to see the stories they have to tell, I pull in to another roleplay until I find somewhere they can call home. Sometimes they end up in roleplays where they [i]have[/i] nothing new to tell me, so I will discard it from what I consider their 'canon' experiences. Sometimes I will tweak a character for a certain roleplay and consider what I am writing to be essentially 'fanfic' of my own character; I'm still writing it, enjoying it, there is nothing wrong with it, but it has no impact on their real story.

As a writer, something that interests me is seeing how minor changes can have a vast impact. That means I do sometimes deliberately run the same plot with the same character with multiple people; I am interested to see how different partners with different things to bring to the table, impact the characters I write. I don't feel this negates the experiences of my character at all and I do believe it helps me develop and better understand the motivations of my characters.

As I said, it's all about what any individual writer is interested in writing. For me, that often means keeping the same characters, who I know and love, and bringing them with me on new journeys. Sometimes it means creating new characters to explore new scenarios with. I both reuse and create and I enjoy both; personally I don't see one as being more beneficial than the other, as long as my interest is maintained and my writing and creativity are allowed to develop.