The traditional explanation for the superstition about bad luck being associated with people who light 3 ciggies with one match (or, in some cases, one solitary flick of a lighter) seems a bit odd, as well: If it’s supposed to have been a war-time notion that an enemy sniper would notice the first cigarette being lit, take aim at the second, and then finally fire at the third… What’s to stop the sniper from firing after the second cigarette? He’s apparently already taken aim, so he might as well take a pot shot at you, whether or not you’re igniting any more tobacco.
The way I was told it was that it was simply a matter of duration. Lighting three cigarettes supposedly took long enough that a sniper or machine-gunner could notice the light of the match, bring his weapon to bear, aim, and fire. It’s not the three cigarettes, it’s the match burning for ten seconds or whatever. Or so I was told.