Even 6 as a scholar is stupid, especially with the heal requirement on the tank. He stomps too often to use your good fairy cooldowns, maybe you can get the hot everytime I haven't timed it, but like I don't know when I'm alone healing the stomps, even if I preshield people, if it's 6 I and everyone else dies before the end of the stomp with my spamming the key. I guess maybe cast 2 then swiftcast 3rd but swiftcast is such a shitty unreliable spell when you need to use it quick. And then after you're done casting you 3 or so Succor, you have to move out of the fucking wraths that spawn right away, then you have to top the tank off who's probably sitting at 40% hp at that point, and then you have to top everyone off over time, slowly, while still keeping the tank up. Shit's stupid, I've only survived one stomp phase when I've been the only healer left when it was advanced enough he had strong stomps. And yeah with no bard you're also oom as fuck and I don't think we have a single bard in our FC, just fucking dragoons and monks.
But you could do it with 5 if you had 2 healers 2bards 1tank I'm pretty sure. Fairy+regen keep the tank up during heart phase, healers in cleric stance dotting the shit out of it and bursting down the rocks if they pop on DPS. I guess maybe replace a bard with a BLM so you have an actual LB to use, use it to aoe both the heart and the first rock(or if BLM is in it then LB the 2nd rock and if BLM in both well fuck it). Need relic/relic+1 and shit though, you're not doing this with ifrit weapons and what not.
On the LB question, we LB on the heart right at the start of the phase. LB1, no point in waiting for 2 and unless you slow down the start you won't have it for heart anyway. You get a LB3 by the time he's low hp later on so no reason to not use it. If your DPS is decent enough you won't need a LB regardless but faster heart is still better/safer. We kill first rock, the one he casts like 10secs into the phase and ignore 2nd rock until the heart is dead, you have the time to kill the 2nd rock when he's doing his little animation shit. Oh and whoever you break free from the first rock, make sure they get a dispel asap, that determination debuff is nasty shit especially in a DPS check.
To be honest in our first tries we struggled killing the heart and shit. But turns out it was just shitty players mostly, not even a gear issue. While the game is fairly straightforward, maintaining an optimal DPS rotation isn't something bad players can do at the moment, so a lot of them do atrocious DPS. If you have a 5DPS setup and you can't break the heart with a LB1, then you have either undergeared people or people that suck a lot.
Oh and if you have people dying before the heart, it's unlikely they'd survive more than 30secs after the heart anyway. Better just keep training because the first few phases are EASY in comparison to after the heart and no one should get hit, let alone die(then again as I said earlier, I get hit often during hit, because eh whatever).
Also point out, we've used 3 healers setup often, it seems to make it quite a bit easier, but it's harder to get the heart if your DPS are shit. Mostly the point was that when a healer dies, it's not a wipe, you can keep going, and also see the no bard comment earlier, it's easier with 3 healers mana wise.