I think the screening really helped on my recent post about 13th Child. There were three broad kinds of comments:

a) those that (I felt) were 'safe' or close to - which I could unscreen as soon as I saw them
b) those that were exhibiting some common kind of Fail - which I wouldn't want to have up there without a reply to counteract them; so I'd compose a reply and then unscreen. Towards the end of the week this started taking longer. :-)
c) one which I never unscreened but took it to email instead, at which its author (a friend) agreed that it shouldn't have been written.

It did slow down the conversation for everyone. In the circumstances, this was very much a feature rather than a bug.