One benefit of the reconstruction of the Muni's Market Street line into the F line was improvement of the power systems. I remember times with the old PCCs where so many were lined up downtown at commute time that the voltmeter on some cars (admittedly not a precision instrument) read below 300 volts. Yes, lights were dim and acceleration was slow, but it didn't matter when things were backed up that much because accelerations were short and speeds were 10-15 mph.

Probably because of the acceleration power demands and frequent traffic, modern light rail systems running running nominally 750VDC seem to have relatively small power blocks and frequent substations. Sacramentos's RT light rail has substations no more than 3-4 miles apart, and frequently closer. Of course, modern substations are more compact and automated than the old ones, so they can be dropped pretty much wherever it's convenient and needed. Also, modern systems are usually designed so one substation can go down and the line can still operate (more slowly) based on power from the adjoining substations. Two adjacent substations going down, though, stops everything.