I saw a show on tv about buttons once. Buttons are different sides depending on whether they are meant to be buttoned by the wearer or a servant, and it has just stayed that way.Uh.. I've never threaded my belts to the right.
Always to the left.
Buttonholes and zippers for women tend to go the opposite direction. Example: the sweater I'm wearing today has the buttons on the left side and the buttonholes on the right. All our mens' shirts here at TB have the buttons on the right and the holes on the left.
But my belt starts just left of the fastener, wraps around counter-clockwise, and the excess goes to the left.