I'm basically saying, once they know the direction they're going, they don't change the finish unless they change the match entirely. Undercard matches might be fair game, because at one point they decided they wanted to continue The Shield, and at another, I believe AJ might have asked for time off after Mania. But once they know where they're going with things, they won't change the big finishes for Mania....I'm fairly certain of that at least for the big show.
Well the scripts are about more than just the finishes, they're the whole show, that's what isn't finalized until late. They don't tend to even time out the event til the day of, since the scripts are changing. The match winners of the big matches are certainly
mostly known well in advance (like Cena, HHH and Undertaker winning the main events last year). What does change and is kept secret is the actual finishes, the endings of the matches. Those are always getting changed. That's why the odds often shift suddenly on the last day, the final finishes were just found out by people in the company who want to make some extra money on the side with bookkeepers (which is most certainly illegal).
For instance, I can imagine that Brock/Taker and HHH/Bryan have had their winners picked since the start, but Bray/Cena and the main event are more prone to Vince going back and forth on who he thinks should win. The only real planning WWE does for WM is deciding what they want the main events to be, well in advance. Usually they'd have winner in mind then, too.
That's how WWE can know five months ago that Brock/Undertaker was a match, but it only has like four weeks of a very weak build. Or how they knew since WM 28 that WM 29's main event was Rock/Cena 2, but that match had a short, absolutely shit build. Planning long term is just not their strong suit because of Vince's micromanagement and the high writer turnover rate.
Of course, Punk leaving, and the fans revolting after the Rumble ended up forcing their plans to change anyway. But they've rolled with it decently enough.
I am honestly amazed that CM punk walked away. Wouldn't he have easily made millions of dollars working up to Wrestlemania XXX? Dude has integrity.
He has millions already, and he seems to live inexpensively, so he doesn't care about any more money.