It really does not matter because the jackhammer consumes 10 mL of gas to smash one tile. That’s nothing. If you run out of gas because you used your jackhammer, you were going to run out of gas no matter what you did.
Also, I don’t recall how this works offhand but I suspect that destroying a house by burning it down will yield the same randomized results as smashing all the walls. It’s just less convenient because only the rubble that used to be walls yields rocks, and you have to remember which stretches of rubble used to be walls.