A complicated banning system should be automized which, in fact, needs to be supported by the bulletin board software. Is it? I don't think so. Also, I don't think I've ever been quick or unjust with banning; I might have been harsh a few times but, well, I'm also human...
By the way, the netiquette recommends that people should keep reading public forums for, at least, two weeks before they post in there. Guess why; to become familiar with what's allowed and what isn't and what to expect from senior forum members, moderators, administrators. With this in mind, even quick banning and harsh behavior may be justified (although that may not be a good idea, from a completely objective point of view).
Furthermore, the forum rules are very clear - I'm happy and proud that my recommended refinements and explanations have been added to them - and, with the big pop-up windows, you just can't miss them. So, is there any real reason to get annoyed when someone calls a newbie's attention to the fact that he made a mistake (e.g. not searching the forum) that is obviously a mistake, according to the obvious forum rules?! And I'm very sorry but, with real life around, most people, including the moderators, don't have time to explain everything, including the forum rules - what, where, how, why - again and again and again to everyone. In fact, it shouldn't be explained at all; people should grow up and understand that they need to educate themselves instead of expecting other people to educate them, especially when that educational service - e.g. this forum - is FREE!