What am I doing wrong? (WHM)

[Loam]

I keep stoneskin on my tank which saves me 2 or more casts of healing

I can't really find out the point in keeping up Stoneskin on the tank during the fight. Maybe there's something that escapes me. Take this video as an example: http://www.youtube.com/watch?v=XS86-eyX1Jk. The WHM keeps Stoneskin on the PLD for almost all the fight, but as you can see, the tank has 4983 HP in total, so Stoneskin saves him from only 896.94 damage (18% of total HP). In the same video you can see that with a single Cure II the WHM restores around 1100 HP, definitely more than a single Stoneskin with the same MP cost (266 in this case). So, I can't really get it. Where is the point in keeping Stoneskin up on tank for all the boss fight? :/

Edit: I forgot to mention that Stoneskin has a cast time of 3 seconds, against the 2 seconds of Cure II.

[Insomniak808]

Maybe you have Clerical Stance on... lulz