The rule is what it says:
It is not losses, it is how wide the UG is.
It is not a minimum, the UG must be the required number of files wide.
So yes, if it loses an entire file, then you could expand it again to meet the requirement of the characteristic. Realistically, I am not sure this is likely to happen very often!
The following is for clarity:
If bases turn to face a flank (or rear), then it no longer meets the requirement for the characteristic.