I helped a dealer do some installs between '01-'04 and one morning, we went to a house that was undergoing a remodel. Since I was only part time, the other guy was lead an after we got there, he walked around with the blueprints fro twenty minutes and after getting tired of him just ignoring me and anything else that was happening, I asked "What's up?". He replied "I have no idea where to start". He had been doing installs for years and his mind was absolutely blank WRT head end and how to get the speaker wires to their destinations.