Drywallers can be a gig help, or your worst nightmare. I make a point of talking to the drywallers on any job where they will be involved in our wire or speaker layout. I find that if you approach it properly, you can make them aware that the wires are important. 9 times out of ten, they will end up poking your wires out for you. If you mark the studs or joists properly, they will even avoid poking them out right beside the framing. Sometimes I even buy them a case of beer or two