[Mathulhu]

I think you need a rule to represent the diminishing returns of just plugging away with the same thing time after time.

If you take the nymph vs guard example;
the being beautiful reaction modifiers can get you a long way but if they are not immediately mind whammied to insensibility to immediately open the door then the nymph is still locked up and can't use that effect again.
The nymph must look for another avenue and method to influence the guard, being beautiful might still help with the new approach.