Husband turned on one radiator (fairly low, to 2 out of 5) briefly a couple times, but we are still going strong with almost no heat. We've hit the mid 30s (lows) a couple times, and are frequently in the mid to low 40s. Actually lows are not really a problem as I like it cool when I sleep, though husband isn't quite as happy that way and I'm debating the purchase of a new comforter to get him on board with no heat in the bedroom all winter.
But during the day, I'm adding layers as the temps decrease, and I find that a good run up and down the stairs a few times when I'm really feeling the chill helps a great deal. Also, a scarf and hat as necessary, though we aren't there yet, and thick wool socks inside my slippers. I also have a buckwheat (I think?) filled neck pillow that I can pop in the microwave and wear around when I'm really chilled. And drinking warm water does wonders.
And while it looks a bit silly, I find that adult onesie-style pajamas keep me warmer than separates. I sometimes wear a layer under them and/or a fleece over the top. But I think the onesie works on the same principal as mittens being warmer than gloves. So that's more normal winter house outfit.
I found last winter that I could be not-uncomfortable even when I could sometimes see my breath in the house. IDK what the indoor temps were (radiator heating, no thermostat), but I'm quite certain they often hit the high 30s, or less.
We also hang a heavy curtain in the winter to close the open floor plan living/dining. That way, we only heat the living room.
I love hearing people complain about spending 2500Eu (~$3400) to fill up their oil tanks annually or more, while mine is still about 85% full after nearly a year.