I did have a full fitting done that included cleat placement. He even put one cleat farther forward than the other to compensate for a slight difference in thigh length left to right. For what it's worth, almost every exercise-induced injury that I've had (past knee problems, pulled hamstring, sore Achilles, piriformis, etc.) has been on the left side.

Maybe I'm just left-leaning physically as well as politically... :-)