^^^^^^
There's extremes. If you run around in a tee shirt your body will struggle to stay warm. If mst of your body is warm, it's easier to keep your extremities from freezing. Note that I also said I would put on wool mittens when I didn't need the dexterity. When my hands get extremely cold I put heat on my wrists, because it stops the pain faster.
In my younger days I once got so cold by the time I got back to my truck that I held my keys between the palms of my hands to unlock the door, then get the engine started. I lay on the truck seat for some time not moving, until it warmed up enough so that I thawed. I still had to get back out and load the bleeping snowsled.
Then there's the old wives tale about most of your body heat escaping from your head. THat's only true if it's the only part of your body which is covered...
One thing which I realized years ago was that wearing a wrist watch would make that hand get cold easier.
There's an old adage "Cotton Kills". It's one thing to wear something while working around the yard, or someplace where you can get to a warm place easily. However, I might snowsled 10 miles, then snowshoe 2 more. If my hands get wet and I can't get them dried back out, it really can be life or death. I also have resisted the electric clothes for the same reason, although a couple of hand warmers are part of my emergency kit. I also prefer wool to most synthetics...