The more I think about this - and given the amount of reprieves I think that it's a flat out penalty. For how long I don't know. Maybe 6 months, maybe 1 year. Perhaps it' varies according to the "crime". Maybe it's never lifted but given the amount of recoveries I think that must be the case.
I think the sites are penalised and the links that google dislikes are devalued, the penalty is run and the site is released and will rank on what links it has left after that (if it's ever let out that is). Whether it matters if the links are removed or not I don't know.