Yeah, no. Before my wireless thermometer corked out, a very weak swarm going into winter (2 seams of bees! 2!) was maintaining an ambient temperature 2-4C higher than the outside...on the dummy board 5 frames away and six inches down from the roof. When the temperature was down around freezing I tilted up the roof edge and stuck my hand on the crown board to find it positively toasty under its insulation, and a quick glance revealed bees wandering over the frames with zero signs of clustering.
The primary driver of store consumption by bees isn't moving around, it's transforming all that sugar into heat through the insanely wasteful process of using their wing muscles. Which they do in the cluster. To produce heat. Which they need to live.
So your comment of 'they would run around all winter to save stores' is very strange. Bees running around in winter are bees in an environment where they don't need to be using their stores much at all. They feel the hive is warm enough for them. What you're saying seems to be approaching the winter stores from the wrong direction. They aren't hibernating - there's not some magical temperature where they feel the need to eat less. Stores in winter isn't food in human terms, it's firewood. Make sure your windows are closed and the house is well insulated and you don't have to use so much of it. Translated into human terms what you are saying is 'at 4C you can keep the fire burning low and use the least wood' and what we are saying is 'insulate properly and you don't need to light the fire (ie, cluster) in the first place'.
