You somewhat had a skewed example. As long as you aren't overhealing their max HP, it's just as well. Using succor during downtime (invulnerability mechanics or prepull) is a good way to prepare, but during active combat, if you are overhealing someone at 100% health, it's less than efficient.
She is comparing medica (not medica II, because it has the same healing potency, without a galvanize effect.)
Doing this ,you spent two gcds on your succors for only 3/4 of the healing potency (450 between shields and heals that weren't overheal.)SCH (reactive galvanize):
Player is at 13k/13k HP
Player takes 3K damage -> 10K HP
1 succor>SCH cast succor for 1K + 1K shield -> 11K +1K shield
Player takes 3k damage, shield breaks, 1k absorbed -> 9k
SCH (proactive galvanize)
Player is at 13k/13k HP
1 succor>SCH cast succor anticipating incoming dmg for 1K (overheal) +1K shield -> 13K HP + 1K shield
Player takes 3K damage, shield breaks, 1K absorbed -> 11K HP
2 succor>SCH casts succor for 1K + 1K shield -> 12K +1K shield
Player takes 3K damage, shield breaks, 1K absorbed -> 10K
Played around with it more and I do take back that Novelty comment. I had a friend parse in Ampa Hard in Expert and had a pull of 2200 DPS (With slip ups on my end.) It kinda fluffed the whole run, since I beat everyone but the BLM at almost 1250 (BLM was 1275.)
What I want to say is: Bliz II is powerful, but it is not useful. It has very few real places that you can use it, where as Stoneskin, gives you the ability to capture inactive time and turn it into Active healing. It also has general other uses, like those moments where tanks need more than Adlo or giving to a DPS with weakness, since it has a duration of 30 minutes and instead of adloing them specifically before heavy raid damage incoming, I can treat them with a general succor (In case deployment is down. You don't really plan death.. in most cases xD.) In Roulettes I will probably tote around Blizz II, but in content that does not have a noticeable portion of adds, Stoneskin will be there. (Now if only they could macro turning on and off certain cross class skills D: </3)
Stoneskin pushes back your need to heal by 1 Embrace on a tank(In a sense as it is a little more than an embrace). Adlo really only pushes it back by 1.5 so it almost keeps up, but Blizz II gives you numbers lol.
On AOE, I usually open with (Precast) Bio II> Miasma> Bio > Swiftcast > Bane > Shadowflare> Miasma II. You don't suffer the extra .5 GCD cast time from Shadowflare and it doesnt clip the GCD if you swift then Bane. If 4 or less targets that will survive more than 18 seconds Aero Spam, and if 5 or more I'll Blizz II.