Thanks, I think about it...
Imho, permanen ban is not really required, if we use formula solution, cause it endless grows automatically (up to maxtime). If you sets maxtime to 365*24*60*60 - it will be a year.
And using the normal distribution nothing should be changed, only "bantimeextra.enabled = true". The default values are good for me, and already tested in production.
But the problem is not this, as I already wrote within my last comment, but the adapting of few bots to a bundle of "maxretry" and "findtime". Soon I will introduce new much advanced solution, consider this problem.
Keyword: IP-related auto decreasing/increasing of  "maxretry" and "findtime".

I'm trying to keep the configuration as easy as possible.