I am currently in a heated debate over the excessive use of Rejuv by most druids with one of our top healers. I find the fact that you can toss 10 rejuvs out to anyone in the raid and spend the next 9 seconds casting heals on the tank and WGing as you please, leads to heal sniping.
Of course we run with a grotesque NINE healers in Ulduar. Not that we don't try to bring more DPS, we just don't have any who log on. Expect information on boomkining it up. Anywho...
Not including HoTs, the tanks health changes every 2 seconds by either damage taken or heals received using the following distribution:
Prob ----- Health deficit
50% ------ 0
25% ------ 4000
12.50% --- 8000
12.50% --- 16000
That's a 1/2 chance the tank is at full health, 1/8 chance he is at down 16k. Basically only half of the heals land at a point where they can actually heal anything. Assuming base 2pct7 you can expect:
Rejuv: HoT 1864, Mana 430
Regrowth: Direct 4544 (non-crit), Hot 1035, Mana 693
Lifebloom: Bloom 3180 (non-crit), HoT 377, Mana 698-489(refund) = 209
HPS = Effective Heals Per Second
HPSC = Effective Heals Per Second Cast including 0.2s per cast as reaction time
HPM = Effective Heals Per Minute
RJ = 19s Rejuv Rotation
RG = 28s Regrowth Rotation
LB1 = Single Stacked 10s Lifebloom Rotation (No glyph)
LB2 = Slow Stacked 18s Lifebloomx2 Rotation Cycle.
LB3 = Slow Stacked 26s Lifebloomx3 Rotation Cycle.
LBR = 3stack Rolling Lifebloom Recast every 8 seconds. No Bloom.
Numbers include Living Seed.
Results --- Heal --- HPS --- HPSC --- HPM
RJ --------5592----294---- 4438---- 14.6
Rg --------7762----277-----3940---- 11.2
Rg Glyph - 9240--- 355---- 4690---- 13.3
LB1 -------3365----336---- 2671---- 16.1
LB2 -------7098----418---- 2817---- 17.0
LB3 -------11700---487 ----3095----18.7
LBR -------3959----566---- 3142---- 5.7
Just looking at these numbers we can see the difference between RJ and LB. To make this simple, Rejuv heals for more, heals more slowly, and results in less heals per minute. While it does a large chunk of healing, you are risking a lot by only using rejuv, in that there is 2 seconds of zero heals coming from you. Of course this is assuming you only cast a single hot, which is retarded.
There is a 5.26% chance that your last rejuv tick will result in a heal while you have a 52.63% chance that the other ticks resulted in a heal. This leaves you with a 68.42% chance to heal for 1864. This cost you roughly 382 mana.
There is a 10% chance that your Lifebloom tick will result in a heal. There is a 70% chance that two of your lifebloom ticks will result in a heal. You have an 8.30% chance that your single stack Lifebloom will result in a heal and a 1.70% chance that it will result in a crit that will heal. This is a lower chance to heal with only 8.3% chance to heal for 3557, another 8.3% to heal for 3934, 1.7% to heal for 5147, 1.7% chance to heal for 5524, 10% chance to heal for 377, and 70% chance to heal for 754. This cost you 209 mana.
2.07% chance to heal for 5579, 1.50% chance to heal for 7851, 2.07% chance to heal for 4544, 1.50% chance to heal for 6816, 3.57% that your last tick will heal for 1035, and 57.14% chance that your ticks will heal for 1035. This means you have a 7.14% chance to heal for over 4.5k and 60.71% chance to tick for 1035. I won't bore you with the glyphed numbers as even I believe that to be a waste.
Obviously these numbers are relative do not take into account your crit, however the percentages would still be the same, just slightly higher numbers to work with.
When I say that rejuv spam is padding the meters, I mean just that. Healing meters do not adjust for druid overheals. Even if you ticked once for 3 health, that still counts as a heal. 100 3HP heals = 300 HP. Assume your rejuv ticks for 1k, assume you have this hot on 10 people, and assume that they each receive one tick per. That's 10k HP healed and all you had to do was put a rejuv on them when they didn't need a heal. This may not sound like a lot, but consider the fact that you have 9 seconds to cast heals on the MT/OT before you need to refresh your Raid Rejuvs. You just successfully sniped 10k healing in addition to whatever healing you are doing on the tanks AND Wild Growth.
You are a druid, heal like one. There is a reason we have so many heals. We have the luxury of being way OP in PvE in every regard, get creative and start healing the way the fits. Stop reading those stupid Healing Meters. If you keep people alive, grats, you are healing correctly, if not, try out a new style, but ffs people, you don't have to heal everyone in the raid by yourself.
LEARN TO USE HEALING ASSIGNMENTS.
That is all.
Edit: Thanks to Erdluf over at PlusHeal