Here is my guess.

For "normal" or "old style" cars, brakes are in two pairs: 1. left front and rear right; 2. right fron and rear left.

Another feature is rear brakes act a little earlier than front ones. In case the brakes are totally rebuilt with empty new lines. The most efficient way to bleed is to bleed the rear first since the fluid will flow to the rear first. If you start with front first, then most fluid might flow to the empty rear lines (filled with air)instead of going to front.

So the criteria is to bleed the ones that act first when you press down the brake pedal.