I only ever went to one quick build, and that was only cos my cousin went and I was staying at his house at the time. We didn't really want to do any work so we said we would do health and safety / security. They let us as well even though we were only 16. I didn't even wear the hard hat, shows how much I knew about H&S. My cousin had done a short course at school I think but the sum total of his knowledge was giving a plastic dummy mouth to mouth (this is in lifesaving terms you understand, not a blow up doll or anything)
The site was full of lasses looking for a guy with their names written on their hats in marker pen. There were some kids who came but couldn't go on site so just annoyed the neighbours by playing football in the street and kicking the ball into people's gardens and windows. Lots of the equipment was piled on the pavements so ordinary folk couldn't get passed. The guttering was put on wrong so that it drained off into the neighbours yard. Some clown decided to put all the plasterboard up and make a start on the decorating before the electrics had been put in. At one point a resident called the police... it was a bit of a shambles really.
The society did tighten up on who could go on quick builds shortly after that. Maybe they heard about us and our botch build.