how long do packages stay in testing?

[Jack Tanner <ihok hotmail com>]

The testing repo has packages as old as openldap-2.3.30-1.fc6.1.src.rpm 
30-Nov-2006 and sysklogd-1.4.1-42.fc7.src.rpm 11-Dec-2006. Is there any policy
about how long packages should stay in testing? AFAICS, if a package shows up in
testing, it's either good and should get pushed to updates in a little while, or
it's bad and it should get yanked from testing. Right?