Reasonably well maintained steam systems are pretty efficient and comfortable. I’ve lived with one.

It was a studio, one main radiator in the room, one smaller radiator in the bathroom. The one in the main room had an adjustable outflow valve on it, so you could moderate the amount of heat coming from it, and there was a big honking ball valve shutoff that ensured you never saw heat once it was turned off for the year (not that I was ever really concerned about that, why would they come in and restart the boiler in the summer?). It literally took the occasional, once or twice a month tweak for comfort, and maybe a few days learning how it worked my first winter there, and my place would be the right temperature all the time give or take like 2 degrees F. Oh and if you really think it needs more whiz bang gadgetry you could easily swap the adjustable valve for a thermostatic radiator valve so that you could set an exact temperature still. It wouldn’t get you much better results but they do exist.

Huge caveat though, I’ve also seen the opposite, some friends lived in a shittier building and their radiator was literally broken, steam sprayed out at the stem of the ball valve and shit, and there was no adjustable valve (though they could have maybe added one). Their place would be so hot while the boiler was running they had to have the windows open in 0F cold and then the boiler would shut off and they’d of course be freezing. But the problem wasn’t that they didn’t have a thermostat, the problem was that their buildings heating system was literally falling apart.

Part of the reason these issues are so prevalent though, is that heating systems of that era were often over specced so that every unit could have their windows open for fresh air even on the coldest day of the year.

Have fun when it’s 90 degrees inside because the heat is on in the summer for some reason because fuck you tho

It’s more efficient.

I highly doubt that it is more efficient.