Personal LB is as boring as party LB. It's just a bar that fills regardless of how poor or how well you play and then you unleash it. It'd be far better to do something like BLM has going for it with accessing a spell or ability for keeping Enochian up for 30 seconds. Just make the requirements more demanding / unique to each job with each job having really different limit breaks (SMN morphing their egi into a full aspect of the primal for a short period or MNKs getting triple their skill speed with no TP costs for a short period of time, etc) rather than just having plain damage, healing, or damage mitigation. That would give incentive for knowing your job and playing it well since you'd want to use your job's "ultimate ability."