Greg responds...

For the last two seasons, Brandon and I skipped the premise stage entirely, and we broke every episode together on index cards, and I took those cards to outline. Then Brandon, myself and the freelance writers are handed a completed outline. (We have no staff writers on the show, and haven't after season one, for budgetary reasons.) So, no, a writer can't come in and say "I have my own really cool idea for an episode." Freelancers are not in danger of being fired; they simply don't have that opportunity on this series. It's too intricately plotted. They do come on at the outline stage, and we talk through everything and try to stay very open to their ideas for the episode they've been assigned and to the other episodes in the writers room that day. But the story is the story. If they decide to bring Wally back in an episode where we didn't previously plan to bring Wally back, it's simply not going to happen.

But no one ever suggests going that far off book, anyway. That's just not this gig, and that's made clear up front.