Fox can shoot two lasers in a shorthop, if you don't fastfall. Since the first laser is so high, it will often miss many characters – for this reason, they have become less relevant in the modern metagame.
Lasers are best in matchups where reaching kill percentage quickly is crucial; namely, vs. Jigglypuff. Since she spends so much time in the air, double lasers are more likely to hit. The same logic applies to characters like Peach and Ganondorf.
The input is not entirely trivial, requiring a quick flick from jump to B, but it is consistent. It is possible to drift during double lasers, which may be an optimisation worth practicing.