I live in a cold climate and I'm very tough to the cold, which comes from a combination of genetics, body size and being accustomed to it. I never ever have to use warmers in any of my outdoor activities as long as I am even a little active and winter temperatures here plunge down to -40 F and colder (not counting wind chill).
HOWEVER... even if you are wearing excellent cold weather footwear... if you are completely immobile for several hours in extremely cold temperatures, with your feet on the bare ground or on a metal platform.. eventually you will feel the cold in your feet.
This past November I was hunting in western Canada and we were hit by an "early" extreme cold front. I hunted from an open portable tree stand in temperatures as cold as -34 F for up to 10 1/2 hours at a time. I wore two pairs of good wool socks, a pair of Sorel Glacier boots, a pair of Arctic Shield boot covers, and a pair of homemade silent covers over that. On the worse days I had to slip in a pair of toe warmers under my toes (placing them over didn't work as well).
Even though the toe warmers don't last all day, they got me through from darkness and those coldest hours of early morning.