I was taught decades ago to keep inside a two-foot-wide area at the right edge of the road, and have never seen a good reason to change.
I'd rather have cars passing me closely than stacking up in a long line behind me. If they're going to pass on a narrow two-lane road where they have to partially cross the yellow center line, I want to give them as much room as possible so they don't have to swing any farther into the opposing traffic's lane than absolutely necessary.