I don't think it is just slackers- some people like to just hear themselves talk!

I attended a few meetings at a job that could have been done in 30 minutes but always inevitably dragged out to an hour or more because of two people- one is likely a slacker who keeps asking questions to which the answers are either obvious or irrelevant and he never actually contributes anything positive.

The other is a brilliant guy but just likes to talk. I was told, before I met him, that if you asked him what time it was he'd tell you how to build a watch.

One company I worked in the overall manager mandated agendas be created- he came into one meeting in which the meeting organizer (my colleague) failed to prepare one. Doug asked where the agenda was and Gary said he didn't create one- to which Doug said "meeting cancelled, get back to work."