I'm not sure about getting more done when your comfy--sometimes when I'm in my garage puttering and have the wood stove going on a cold winter day,I tend to want to stay near it and feed it ,and get warm instead of working--next thing I know I have dozed off!....if you keep it just warm enough not to be shivering,you end up working more..
I like having it just warm enough in the garage so tools dont feel like icicles and threaten to stick to your hands..
Working when your chilled to the bone is no good either though--you tend to rush or do things half-ass just to get it over with,so you can go get warmed up again !.
Sometimes I feel its just as much work getting the wood stove going,hauling logs in,splitting them,etc,than the "project" I intended to do would be..then there is the 1+ hour delay between the time the stove gets fired up,and it actually gets warm enough to feel comfortable..I cant use my torpedo heater much any more,I start gagging as soon as I turn that thing on lately..