What is a reason for DEROS extension along the lines of best interest of the Air Force?

Many reasons one can find. Manning issues, upcoming inspections especially if your over many key programs, wanting to keep the continuity. Big one right now is saving the AF money by extending overseas. The less you move the more $$ the AF saves. Look at the current entitlements for certain jobs. $2k bonus, or 30 days leave, or 15 days leave with ticket to closest Stateside port. This only applies to low manned jobs but you only have to do a 12 month extension to recieve one of these.