Coast 3-way -- does this conform with Code?
Perhaps I could be wrong on this but when I worked as an electrician in California many years ago, the coast 3 way switching was developed for the following reason. Many homes and offices were wired using steel flex (aluminum came later). Most cities in California at that time had their own electrical code, governed to some degree by the state code and NEC. There were some rules that did not allow you to pull four wires (Conductors) in a 1/2" flex conduit unless one was a switch leg.

By using a coast 3 way the conductors were as follows: one point wire (Common) one switch leg, one Hot and one neutral, with no travelers. Plus of course if you needed a hot plus a switch leg and a neutral at each end, you would have them available. On a standard 3 way switching you would have two travelers (In the UK these are called Strapping wires).