I like the idea of pools. These pools have an expiry date. You have a candidate. They have met all the criteria, have gone through the interviews, have scored, and as a result, they're in the pool. But sometimes these pools expire in a year.
I know some managers can extend that period of time. Coupling with what Debi said earlier, if you have government-wide pools that stay for a long period of time.... Just because I'm qualified today, that doesn't mean in a year I'm no longer qualified for that promotion.