My wife builds off of masters that are submitted to the county but the electrical plan is just a guideline that sets the service size, major appliances and the general location of the devices. It is far from a point to point wiring diagram. With all the options and walls that can be moved around it is still up to the electrician to insure code compliance (receptacle spacing and such). Which circuit a general lighting outlet may be picked up on may also be a local call.
In the end a lot of the actual placement ends up spray painted on the floor.
This is an example of a master that was marked up to be "lot specific" and that is about as precise as it gets.
(big file)
http://members.aol.com/gfretwell/2109plan.jpg
