Scrog ?

I'm thinking about trying scrog on my next grow, but there is something I'm not terribly clear on. From what I understand, you stay in vegetative until you have filled up the appropriate amount of holes you want, is that right? If so, should I be cutting off the excess leaves underneath as I work the nodes into their places? I mean every scrog I have seen, the underneath is almost completely bare, are they trimming all of that off?

Thanks!

imo there is no reason to prune anything except small stunted budsights on the bottoms of huge plants which develop into airy insufficient buds that waste resources. fan leaves that don't get light will be cannibalized by the plant at some point