Say I'm a high level cleric. I have a snotload of turning attempts, and I want to turn myself into a killing machine.

As far as I'm aware, by RAW, there's nothing preventing me from using my turning attempts to DMM persist e.g., holy star a few times.

Is this really allowed, or have I somehow missed a rule somewhere which prevents this? Bonuses of the same type of course don't stack (barring circumstance bonuses which arise from different sources), so the AC bonus couldn't be ridden into infinity, but it sure does look like one could be dealing multiple CL/2 d6 beams of fire damage each turn as a free action.

If it is allowed, one could imagine a high-op game wherein a cleric persists even more holy stars (possibly using energy substitution to change the damage type of some or all), and maybe uses metamagic rods of greater maximize to allow himself to dish out hundreds of (admittedly, single target) damage as a free action every turn, or have multiple stacks of spell turning (which I understand do not stack, but he could keep only one active at a time and rotate them out).

Thoughts?