You'd think that at least initially, individual towns would stand up fully connected (albeit small) but isolated networks. That before very long, the idea of connecting one town to the next would occur, and it would be realized that you only need a relatively small number of "long distance" lines, connected between the existing switchboards. At which point, if you were wiring up a city, you'd follow that pattern; tiered layers, as you say. It stands to reason then, that Stockholm's system must have started very early, and had absolutely explosive growth, to get to a situation like that tower.
They mostly did, but the limit on distance is pretty tight - according to Wikipedia [0] local loops were limited to 5 km in length (without extra equipment). I imagine that Stockholm's system here both started early and was in a very dense neighborhood of Stockholm, where direct wiring like this was still a tenable solution.
