Always best to bleed the entire system if it's been opened up, even if it's just on one end. Or even one wheel for that matter. Cheap insurance.
Off topic, sort of, on new cars, they use a diagonal split braking system. So that means that, depending on vehicle, you could have a sequence of RR-LF-LR-RF, and in some cases, having to bleed 1-4 bleeders on the ABS module.
