On the issue of what counts as sufficient “penance” or apology, let me throw this out there:
One common facet of many of the bad acts referenced in this thread is that they often involve abuse of power or exploitation of power, often targeted at women.
So it seems to me that one key aspect of redeeming oneself would be to spend some time down in the lower part of the pecking order.
For example, Louis CK IMO should probably spend some time as a secondary or supporting player on someone else’s show, play well with others for a period of time, arguably work under the leadership of some women to show he really is over his sex-weird-power-trip-thing and then work his way back into the spot light.
I actually think unless these folks actually experience being on the lower end of the power spectrum again, they will never truly reform; and being able to tolerate being shat upon is probably IMO the strongest sign of reform.
Another way to put is these abusers/exploiters have blown the credibility and power they earned, and now they need to go back to the lower spots and pay their dues again, work their way back up.
I think the idea that you have to step down a few rungs and earn your way back up to celebrity/political power/what have you is key.
B/C to a large degree I think a lot of this stuff is about power.