In practice, many SES employees in the metro DC area hold jobs at the same agency/office for their entire SES careers. There is no guarantee of this, and some agencies or cabinet departments like to shuffle the SES assignments more often than others.
DiSA, for example, seems to reorg itself roughly every 4 years, and the details of the SES positions and assignments often vary when the reorg happens. ARL, by contrast, seems to keep its SES and ST people in identical assignments for many years without making significant changes.