I wrote the following up yesterday to someome that PM'd me and I think it may help. Bottom line is the program overall looks at total inventory vs required inventory (requirements) to meet the budgeted mission that is submitted to Congress.. The gap between the two is greatest when it comes to fighters.
The program is dialed up (longer contract years, up-front money, uncommitted category, no TAFMS restriction, etc) when retention is low and or we have a large inventory/requirement gap. In the case of fighters it is not so much a retention problem but and absorption problem. The past few years airline hiring hasn't quite happened, retention has been ok, and the operational requirement (FY authorizations and budget) has lowered, and a majority of Rated personnel were allowed to participate in Voluntary Force Management programs. Since the program is changed yearly based on current conditions, some of those items I mentioned above like TAFMS, uncommitted category, etc would be utilized to try and retain folks. It pretty much comes down to: does the inventory match the budgeted requirement. Hope this helps some.