Desert Camel , it just means that you have waited too long to apply or are looking for bases where the demand is so high that there is no more position available...
I got the base of my choice and there are at least 8 other pilots from FZ on their notice period or already gone who also got what they wanted.
It is obvious though that it can not last forever as it depends on the number of aircraft per base versus the number of pilots requesting it.