Do not know if what is said by SANDF/SAAF can be believed anymore, but if true, the Gripens are utilized on a rotational bases. As I understand this, not all can be used at the same time and therefor some are "temperately stored" and then roted back into use from time to time.
This is mostly cost driven but from what I could gather when I talked to one of the pilots at the Swartkops show, was that there are not even half of the required pilots, so how the rotation and scheduling works is an unknown. This pilot didn't want to say how many pilots there are or what shortages they have, but it was clear that there are less than half from what was said. It was also clear that some of the "available" pilots are no longer in the SAAF proper, but is part of the "reserve" force.
My understanding is that there is a considerable shortage of pilots, but as much of a finance problem with way less hours available than should be flown...