Would suggest when using the adhesive warmers to take them out of their package before you go hunting and put them in a quart Zip Lok freezer bag and seal it. The packaging they come in is very noisy to open in the field and when you take them off your bottom layer when finished hunting, you can put the peel off paper back on them and put them back in the Zip Lok and seal it, so they can be used again. They only work when exposed to air so shutting off the air supply will give you at least 2 hunts from each warmer.
In bitter cold I also use a Mega warmer (larger size than a hand warmer) for my right pocket and a smaller hand warmer for my left, or use a Grabber muff with a single Mega warmer in it.
Also use toe warmers but hunters must understand that because air activated warmers of any type work solely on the amount of air they receive. When using Muck or rubber boots for scent control purposes, the only air that gets to the toe warmers has to come in through the throat of the boot as the body of the boots are air tight. In other words a very minimal amount of air feeds the warmers so they won't feel as if they are doing anything, but they are doing a little. Toe warmers were designed for outside construction workers that wear leather or Cordura exterior boots, both of which allow a great deal of air flow when compared to rubber or neoprene. When I wear my Baffin Titan pack boots the warmers receive more air because the throat of the boot is larger to accommodate the liner, thus allowing more air to get to the warmers.