Uhm, I'm confused about the OP. If you don't have a full LB1 by the time you reach the heart phase, isn't your party horribly overgeared and dpsing superfast, to the point where you shouldn't need LB1 on the heart phase?

Also, LB1 still charges as normall, it's only the LB2 and LB3 bars that charge slower when you have identical jobs on the roster.