I keep the temp until I actually have the permanent workers doing their jobs at a normal(sufficient) rhythm. Especially when I have to maintain a certain level of productivity. And if we stick to sport, if my players are scheduled to be back sometimes in the current month, I don't trigger a clause to lose depth at the start of said month instead of doing it at the end of it.
Even if we assumed that somehow the medical staff guaranteed that the players would be 100% back( which is likely BS and meant to shift blame away from whoever decided to reduce squad depth, which could be Murtough, the owners, ETH or all of them). The execution is stupid, if I have a carpenter out and his doctor tells me that he should be back within a month, I don't get rid of his replacement a month early because I still have contracts to fulfill and if I do get rid of the temp then I am 100% responsible for whatever happens whether it is a relapse or an inability to work at the required rhythm for a weeks/months, it will be my decision that put us in that situation, not his doctor.