I'm going to look it up, so don't answer for me...but all I'm thinking is..What the hell is a Good Morning? I've heard, and I think I know..but I want to be sure..
As for the original question...I'm still a newb to DLs, and only do them once a week for now, using heavy as possible.. I was thinking of doing them with light weights 2x a week, but I want better core strength, and I figure 6-8 weeks of heavy ass DLs should help, at least for now..
EDIT: Just checked Wiki and ExRx...GMs look tough, and I don't think I have the room to do them in my micro-gym...but I will try with a real light weight just to get form and rom figured out...