Lightning protection will only be as good as the grounding electrode. Also, on longer lines the equipment grounding path provided by a neutral can have enough impedance that the cable needs to be rated for the phase to phase voltage or almost the phase to phase voltage.
Duquesne Light Company in Pittsburgh, PA likes to use 23 KV cable on 14,400Y24,940 volts. The neutral is of pretty good cross section for the feeders and most lines are substantially less than 25 miles long.
However, Cleveland Electric Illuminating Company in Ohio likes to use 46 KV cable on 19,920Y34,500 volts. This partly because a full capacity neutral really only exists back at the supply transformer and the load transformers are connected phase to phase. Close to the supply station this amounts to a 230% insulation level but at the far ends of the circuits amounts to about 133%. Some earth faults might flow back through the overhead ground wire or the neutral of the 7,620Y13,200 suburban distribution, but there are also line segments without an overhead ground wire and the distribution is 4,400 volts 3-wire ungrounded.
So, whether you use 100%, 133%, 173%, or even 250% insulation depends on a lot of factors.