It took me a few hours for each, I didn't count specifically, but each seems to have around 24-25 weeks worth of story, about double what 2011 had to offer story wise. Go into options, cut out the entrances and work on a system when the game throws a handicap match your way (there's quite a few) keep it on easy and don't do anything fancy, spam moves and just wait for the computer to put that 'Y' above your opponent's head.
- Most of the backstage fights you have to do an environmental KO, so when you see that 'Y' appear, just Irish whip the opponent into an interactive surface and then tap Y. (tapping y when it first appears just usually results in a half efforted irish whip on the AIs end.)
-when you start a match as SOON as you floor an opponent, try and pin him. If the pin (B) button just picks them up, its a guarantee you're going to have a few cutscenes. in this case don't go for a pin, just spam moves to weaken your opponents.
-Whenever you're given a cue to weaken someone outside the ring, its a fair bet you have to give them a finisher, 9 times out of 10 if its a 3 or more on 1 assault a finisher will down an opponent indefinitely, giving you some breathing room with dealing with others.
Hope this helps.