User blog comment:Meighan/Wiki Wisdom: Reacting to Trolls and Vandalism/@comment-4166299-20111111004152/@comment-1393830-20111111005811

Im not a fan of permanent blocks. Always give the person an expiry time unless they are a repeat offender. Your user with 9 accounts is an extreme case. For any other case, a small block should come first, usually a few days. If they continue their actions after that, a few weeks. If they continue after that, a few months. Finally, if they continue after that, a permanent block. And never perma block an IP as you could be blocking many innocent users as well.