What the hell is 'ivalice boss 7'? The math robot? cos that doesn't exactly require healers to know what they're doing, it requires people to 'not stand in the rotating cone aoe', 'dont greed for the drill proximity thing' and 'have basic understanding of maths'. The only 'heal really hard' part that comes to mind in that fight is right after the maths, where your max HP jumps back to normal but you're left at single digit health. Which can be dealt with entirely via OGCDs, as usual. The only 'primed' happening in that fight is when he tells you to make your HP be one haHAAAA
And I farmed SOS 99 times for the mount, I don't really recall there being a time where I was 'primed' per se, any time 'oh big spooky damage' happened I'd have something to deal with it. Looking at a certain site that shall remain unnamed, apparently I was AST for a lot of the SOS runs? Weird, thought I was mostly a WHM main by then. Anyway, if I was AST, then that'd mean I'd have CO, CU, Earthly Star, Horoscope, and all four of those have a 1min CD. you could ration them out and have one used every 15 sec, they're SO frequent. It's ridiculous