[quote quote=1314241]I think on your left applies more to trail riding to let people know you will be passing on the left lane.[/quote]
On your left was only one example I cited. The prevailing traffic conditions dictate the maneuver. The main point is that the bike or person you intend to pass acknowledges you are there and has control of their bike.
A warning not heard because a rider/walker is engaged in conversation, is listening to music on a headset or speakers, or just does not understand English is of limited use. Passing children is a particularly delicate operation because of their divided attention and inexperience.
Last year I was following a rider who was taking selfies. One hand on the grip and his mind focused on getting that perfect picture of himself. Definitely not ready to react. I waited until the photo session to end before passing. I guess a variation of this technique is the talking/texting riding style as well.