Gentlemen,
I use both hands.
Even though for the past few months I am reduced to one pass only because of an injury to my left hand, I still use both hands. I tried to use the right hand only on both sides, but it did not feel right, like driving backward.
I gave up and chose to shave with both hands, even if it meant only on weekends, and only one pass. The rest of the time, I use my loving double edge safety razors, which I have used throughout the years, anyway.
So gentlemen, for me it is both hands.
Regards,
Obie