I didn't want to post on this at all because for a while it seemed like more of a passive (or not-so-passive) aggressive flame war. But whatever.
About using a totally new character, it depends on the situation. Yes, ideally RP would be ongoing character pieces with other characters you know and interact with. But a lot of people have school and/or work and just don't have time to be on a lot, or have to take long breaks from the game, and having these ongoing relationships between the characters is difficult, especially when so much goes on when you are away. Sometimes people just want an "episodic" RP, where some event happens that captures the character's attention, a group forms, and stuff happens. This is what a lot of GM events seemed like to me and I really enjoyed them. Plus, they put you in a position to meet other characters who can continue the RP after the "episode" is over. So, I think using a new character for "episodes" in this way is ok because it brings other characters together.
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