There isn't really a rule, they just have to be in the rankings. There's been a couple exceptions in the past with open challenges, winning number one contender battle royals, or pinning the champion in a tag match but it's a rarity and usually only done to bring an relative unknown into the spotlight.
Tbh I had the thought in my head of the time limit draw before the whole CM Punk/Bryan Danielson news. I'm just a fan of that style of booking. I agree with your point about TNA though. I feel like so far they've done well with that. Jericho putting over MJF and Cassidy, giving Sammy the rub, Sting with Darby as you said, Taz with Starks, etc.
That's fair. I wouldn't mind if you dismissed it anyway lol I'm just having fun sharing my opinion and reading yours. I guess Cody was already a WWE guy as well, so you could see it as WWE guy v WWE guy.