There are plenty of folks here who only use the dominant hand. IIRC Glen only uses one hand. I couldn't use my left to start with and just used the right. After learning how to shave and getting some technique going I tried again just on the check and found it a bit easier as I already knew what I was doing. Slowly I expanded till I can now use both hands. The right is still better but for some it does make it easier being able to use the left