I'd say that the turbine hall pic is accurate for that era. Here's a 1950's pic of the main turbine hall at one of the Yallourn, VIC steam-cycle power stations. From the Museum Vic SECV photo collection. http://collections.museumvictoria.com.au/articles/3519

[Linked Image]

I don't really know what the main limiting factor in steam turbine/alternator set size was back then - but I suspect it was on the alternator side.
Overhaul intervals would also come into play - if they were relatively short, it would be logical to have a greater number of units, to allow for one or two to be down for maintenance, without affecting output too much.

Cheers,
Gadge

"ODK Mods can explain it to you, but they can't understand it for you..."

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