I agree with what was just said about efficiency being less important when the wood is free. Efficiency is still important though, because the good stuff might be scarce, and its good to carry enough for the next fire, and efficiency can mean less work saving energy, and efficiency means less smoke, and efficiency oftem means being able to use damp fuel, though not always.

Still, I think a simple can type hobo, properly sized and holed for conditions (somewhat larger for winter) is very competive and often superior to a manufactured stove like the bush buddy. Also, adjustable windscreen type stoves/fires are usually worthwhile improvements over 3rock type stoves, and can be just as compact. In some places you can use more rocks, or a dakota pit, or a Finnish log candle type stove so even a windscreen isn't always a neccessary improvement.

Three things for certain:
1. Global Sustainability often trumps Leave No Trace.
2. Easy to over-generalize with fire and stoves.
3. Messing with fire and stoves never gets old.