An interesting thread, I have lost count of the times I have been confidently told by pilots that the Maximum Contingency rating found in Military documents and typically of 2 1/2 minutes duration is available either once per flying hour or once per sortie or once per day. Nick's information would conclude that it is once only in the life of the engine and after it has been used the engine is irreparably damaged and is destined for a gradual decline in power output.
It is a question of interpretation - how long is a transient limit allowed to be used - 1 second/5 seconds/20 seconds and again how often is this transient allowed in the life of the engine?