Except in the playoffs(which a championship fight is compatible to), where you only have 2-6 days prior notice depending on the sport.
With a playoff system, no one team is defending it's championship, while the other team is playing to earn it(Like in MMA). Both teams are playing for a vacant championship. That be equivalent to UFC having a tournament style system and having everybody fight, but only one guy wins the belt. Then the next year, the fighter loses the belt, and everything restarts.
The real reason why Jones denied the offer to fight Chael was not because how how dangerous an opponent Chael was (Or this case, wasn't), but because they wanted to deny Chael from skipping everybody he would've had to fight, and going straight to the title shot despite coming off a title shot loss. Greg Jackson loosely outlines this in the video.