The reason for looking left first is to mentally record the position of an on coming vehicle, the looking right gives you a prospective of the vehicle closest to you, if the vehicle closest to you is far enough to pose no danger, you will then look left and compare the position of the vehicle in the previous look. This will give you a prospective of the speed the vehicle is traveling at, and the speed at which you can cross the road. As soon as you decide to cross, you will look right again to ensure the on comming vehicle is far enough not to pose danger.

When overseas, using the look left then right then left, poses more danger than if you swap the method to right then left then right again.