Meaning they must reach total time logged in : x number of hours;
Won't work, they'll probably just use an auto-refresher/script that sends a GET request to the forum in intervals.
or a requirement to be invited(merit), before brand new accounts can write, post.
It'll be hard to get into the forum without some form of connections and they'll probably pay someone to give them merits.
or limit their post to the beginners & help.
I think theymos stated that the newbie jail won't make a comeback so I guess its out of the picture as well.
Mitchell's bot seems to be working well atm in detecting them though so there's that going for us.