Seems like there is a significant difference in modes of heating and cooling the body, due primarily to the vasoconstriction that the body uses to conserve heat in the core. To wit: if I am hot I can cool off pretty effectively by way of my extremities, since blood flow to them is good, and with their high ratio of surface to volume I can expose a lot of skin, and thus a lot of capillaries, to the cold air or water and thus get a good cooling effect. But at the other end of the spectrum, if I am cold and my extremity circulation is reduced, I cannot as effectively heat by way of the extremities. Doesn't mean you can't gain some warmth that way, it just won't be as effective as cooling by that pathway.
I also think that in this discussion we should be cognizant of the difference between warming when you are simply a little cold and warming when you are hypothermic. That is to say, you may feel cold and may have some vasoconstriction going on and yet your core temperature could still be normal or very nearly so, and you still have feeling in your extremities - you are not hypothermic, just cold. in that situation not only is it easier to warm yourself back to comfortable (simply because you don't have as far to go), but also you have fewer limitations on how to do it, and fewer risks involved with overdoing it or warming too fast.
But getting back closer to the original question, I've always tended to go for a roughly equal layer of insulation all over, and that has always worked well for me. Just as a puffy jacket and shorts doesn't make sense to me, Thin pants with a thick torso layer seems inefficient. Of course this is modified by the practicalities of layering and the ease with which some areas can be covered and uncovered, while others have to stay more or less the same. I can't easily adjust what I have on my feet while I'm on the move - whatever footwear I'm wearing, be it shoes, boots, or ski boots, they only fit right with a particular thickness of sock. So the feet are not where the adjustments get made while on the move. Hands and head, conversely, are very easy to adjust layers on, and so they are a great place to fine-tune the thermal envelope. Legs are harder than arms - though shell pants with zippered vents can be very effective.
I also think that exertion level and the particular activity make for different choices. When I used to run in cold weather, I would find myself plenty warm except for my hands - in fact I could be sweating and have my hands quite cold. So I'd run in shirt, shorts and gloves - rather counter to my usual even layer, but for that activity it worked. So the arm warmers on runners may be an extension of that.