Happy days! They wouldn't pass muster under modern regs but they were rather convenient!
I ripped out some old style theatre lighting in a firing range a few years ago. A whole rack of six-channel Strand dimmers controlled 48 600W halogen lights, each one fed by an individual cable and terminated with a 15 round pin socket on each lighting bar and each individual light wired with a round pin plug. With all lights fully on, the setup pulled almost 30kW from a three phase distribution board..
Each light now replaced with an LED multicolour fitting running at 20W and daisy-chained off of a single 13A socket drawing a total of 1kW. I still have 48 of the plugs and sockets, plus the MK steel pattress boxes in my shed. You never know when they might come in handy!
And I pulled out over 5km of high temperature 15A rated flex between the dimmer rack and the light fittings too. Replaced with 300m of 6A standard 3 core flex! And a single 13A plug on the end.
The worst thing about the old theatre lighting was that even with all the lights apparently 'off', the dimmers used to keep the filaments barely glowing, but warm, so that they didn't suffer from shock when suddenly bringing them up to full brightness from cold. Around 5W per filament, 24/7/365 works out at 2.1 megawatt hours per year just in standby. That's about nine times my household consumption. Just to stop the bulbs blowing.
LED saves a bit of energy in a domestic setting, but on an industrial scale it really adds up. I've reduced their electricity bill by around 15% but the trade-off is that they do need a little bit more gas for the heating!