Most managers would probably shy away form this. If you were to have training difficulties and be involved in a TRB (Training Review Board), the FacRep could use this as a means to get that time reinstated. For this reason, most managers would probably shy away from it. With sequestaration and anything being possible such as academy shutting down, they may decide different. If you were being held back from a pay raise indefinitely with the academy shut down, then you might be able to convience them of the idea by bringing up the loss in pay vs certification date. They might decide to take the risk then. They (management) are always worried about past practices being used later and might do any number of things to avoid it. In other words, they let you do it. Then everybody behind you gets the same thing. TRB and all. Management is funny that way most of the time.