Hi.
I think the rotation is really dependable in different situations.
For example. On all pre ICC heroics you can simply spam AB on bosses.
But when it comes to raids, its a bit more complicated.
It all depend in which part of fight you are right now. How much mana you have left/how many cooldowns you can use to get mana back. Depend on your raid guild mates. For example priest spaming hymn or shamans using mana tide..
Mana wise rotation is 3x AB -> AM/MBarr
Nuking rotation ix 4x AB -> AM/Mbarr
To sustain constand dps on different fights which have a lot of aspects etc. you need just to learn how to switch your rotations. It's nothing (at least I think) You can learn here. All we can give you are tips. Rest is on you
Hope this is a bit even helping.