6 lustrates on 6 people? It'd be quicker to just cure III =P
Seriously though, SCH single target HPs is a little dependant on the rest of the group not being low enough to suck embraces from your intended target. T13 phase 2 after Rage of Bahamut is a perfect example of this issue. On SCH I don't want to waste charges at that point, preferring to save them for the flatten/breath later on, as well as a potential clutch save for megaflare. As a result, even whilst mashing an embrace macro, keeping the MT up is surprisingly rough. At that particular point it's noticeably easier as WHM purely because of how unruly EoS/Selene can be.
Stuff like T5 and T9 was always the opposite, no one else was usually low hp hence the feeling of 'SCH = single target kings'.