It's referred to as a tour of duty because most of us are on 2 year appointments. At the end of that 2 years, there's an optional 2 year extension. These orgs haven't been around long enough for anyone to run out their second two years yet.

Personally, I love this format. It never would have even dawned on me to consider applying for a career position in the federal government, but when the job is time-limited, there's some decision making bug in the brain (even though I could have applied for a normal career position and then just left after 4 years!).

It's a great way to entice people to apply who never would have before.

We also need people in for the long haul. But lets solve one problem at a time!