As I said, situations vary. The situation in very high density areas like London in particular is often different. Around here the system I described is the norm, whether it be a 50's estate or one built in this century, of course the earthing practices are different between the two.
Possibly my choice of the phrase "main road" was a bit misleading, for example if we have an estate with half a dozen parallel roads each is on one phase, and the road joining their ends has all three phases with a junction box at each T junction.
Greg