I'm not saying that healing advice can't fit into short tidbits and neat packages. I actually think Matticus' advice is a pretty good starting point for people who are wondering how 4.0.6 will affect them, or people who are starting to heal as discipline priests after the patch comes out. For example, his AoE healing advice (5 players) is to cast Prayer of Healing. Good advice!
But as I discussed on Wednesday, you can actually increase your throughput by alternative Power Word: Shield and Prayer of Healing. In fact, on Wednesday I forgot to include that using a Shield between Prayers would allow you to get a tick off of the Glyph of Prayer of Healing, increasing Prayer's effect by 6.5%1 and meaning that this alternating cast heals for almost 13% more than prayer alone for only about 7.5% more mana per healing - again assuming that your Rapture proc time will decrease to once every 14 seconds from once every 15.
There are other crazy interactions, however. If you are in for a long period of AoE healing and you cast Penance on one of your targets then while Penance has clearly worse numbers than Prayer, it stacks Grace on that person, giving them 24% more healing from Prayer for 15 seconds. That's an increase of 4.8% to the effect of the prayer as a whole, or more if you were only intending to heal three or four people. You can also haste the Penance with a Borrowed Time without consuming the Borrowed Time so it still gets used on the subsequent Prayer. By squeezing in Penance and Prayer of Mending in the same Borrowed Time window, you get an additional tick of Prayer of Healing. These shenanigans have the potential to get you around 0.8% less healing for around 1.6% less mana, which is hardly any different unless you have your 4-piece set bonus in which case you are spending around 28% less mana by doing this instead of just alternating Shield and Prayer.
Of course if the damage is being dealt equally to all people and there is no additional damage being thrown around, then you won't want to use tactics like these because there will create differences in the health of the people you are healing which will cost you efficiency later. That is, unless you know damage will be coming in for a long enough time that you will be able to give everyone a turn getting the boost. Or if the tank is if the group you are AoE healing then you can do this on the tank while AoE healing everyone else.
So, my AoE healing strategy for discipline priests would be something like this:
1. This is 6.5% rather than 10% because this glyph does not help the Divine Aegis portion of the Prayer.