particular military application where ‘at risk’ periods are accepted
A number of examples exist in practice.
For instance, STOL certification is not embraced by civil regulators as far as I am aware. MIL, on the other hand, requires this capability for some platforms to do what they need to do.
It follows that the military spend a lot more time and effort on flight test work up to operational release than is necessary for civil Types.
Horses for courses.