Sgt_Kickaxe - 5:09 am on Sep 15, 2012 (gmt 0)
It stands to reason that if a human evaluator decides it was your intent to cheat that they have a permanent be-gone button. If they feel, on the other hand, that your site just isn't quite ready for that top ranked spot the manual -50 is likely going to expire.
I know of a site owner who doled out backlinks publicly on his blog if others would write about his blog and link to it. Google got upset and made it so he could not rank in the top 25 for anything. His blog wasnt removed from Google but page one was off limits.
When the penalty expired 2 YEARS later he shot to #1 for a lot of keywords and got an instant 250,000 visitors a month.