No, PoM is nearly always used as a dps cooldown. For example, getting more Holy casts on a large trash pack or extra Glares on a boss. Remember dps on trash pulls is important since Holy will stun all mobs, giving you a nice window where your undergeared tank isn't taking damage and the adds can be burned down.

Speaking of Cure, once you unlock Cure II you generally prioritize that. Freecure is a trap. This is especially true for an undergeared paper tank where Cure spam probably won't keep up with the damage. If it burns you out of mana, the run was probably hopeless, but remember to keep using Lucid on cd.