While faceturbating today, it struck me that the position in which you place your free hand relative to the razor would entirely depend on whether you were shaving WTG or ATG.

Sorry I don't know how to post a diagram here, but bear with me. WTG, you want the stretching hand behind the blade, away from it's direction of travel. ATG, you want the stretching hand in front of the blade, i.e., the blade coming toward the hand. Doing otherwise would actually make the whiskers lie flatter against the skin rather than expose them.

Think about it. See what I mean? Or is this something everybody else already understands?